🚀 go-pugleaf

On Tue, 10 Jan 2012 17:29:35 +0100, Jeroen Belleman
<jeroen@nospam.please> wrote:

>John Larkin wrote:
>> On Tue, 10 Jan 2012 01:28:22 -0800 (PST), Bill Sloman
>> <bill.sloman@ieee.org> wrote:
>> 
>>> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
>>>> Just thought some might be interested in hearing our recent guest on
>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>> Magic" fame[...]
>> 
>> Yeah, his book is half nonsense. If you can tell which half is which,
>> you don't need the book. His ideas on "return currents" and bypassing
>> are absurd. And the writing is dreadful.
>
>I haven't got the book handy, but I'll pick it up tomorrow or so.
>Do you mind expounding on why his "return currents" make no sense?
>Did he mean something different from image currents?

He says that a transmission-line pcb trace must always be "referenced"
to the same "return current" plane it started with and shouldn't pass
through vias to become referenced to a different plane, or else the
return currents will get confused or go on strike or something. If
that were true, 98% or the multilayer boards on Earth would quit
working.

He also says that you should add bypass caps and stitching vias to
conduct these return currents whenever a trace does via to a different
"reference plane." 

All silly.

John

On Mon, 9 Jan 2012 22:47:01 -0800 (PST), "David L. Jones"
<altzone@gmail.com> wrote:

>Just thought some might be interested in hearing our recent guest on
>our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>Magic" fame:
>http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform-wizardry/
>
>Lots of history of the book, signal integrity, Gigabit Ethernet
>development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>other talk over almost 1 1/12 hours.
>
>Dave.

Howard Johnson?  Wasn't that a restaurant that you went to for clam
strips ?:-)
		
                                        ...Jim Thompson
-- 
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

On 01/10/2012 01:47 AM, David L. Jones wrote:
> Just thought some might be interested in hearing our recent guest on
> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> Magic" fame:
> http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform-wizardry/
>
> Lots of history of the book, signal integrity, Gigabit Ethernet
> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
> other talk over almost 1 1/12 hours.
>
> Dave.

HJ has a mixture of good stuff and complete nonsense.

I hope you grilled him a bit about his less sensible stuff, like that 
hilariously erroneous video where he attempts to use electrostatics to 
demonstrate that ground currents want to flow under traces.  Of course, 
the impedance levels are millions of times too high for inductance to be 
a factor in that demo, but never mind.    Have a look at 
http://www.sigcon.com/Pubs/news/8_08.htm for the whole ridiculous thing.

(The current path is determined by corona discharge at the sharp corners 
of the metal squares--if you look at all closely, you'll see that the 
discharges always want to go out the corners of the squares.)

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

On Mon, 9 Jan 2012 22:47:01 -0800 (PST), "David L. Jones"
<altzone@gmail.com> wrote:

>Just thought some might be interested in hearing our recent guest on
>our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>Magic" fame:
>http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform-wizardry/
>
>Lots of history of the book, signal integrity, Gigabit Ethernet
>development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>other talk over almost 1 1/12 hours.
>
>Dave.

Did you have to pay him? How much?

John

On 2012-01-10 17:50, John Larkin wrote:
> On Tue, 10 Jan 2012 17:29:35 +0100, Jeroen Belleman
> <jeroen@nospam.please> wrote:
> 
>> John Larkin wrote:
>>> On Tue, 10 Jan 2012 01:28:22 -0800 (PST), Bill Sloman
>>> <bill.sloman@ieee.org> wrote:
>>>
>>>> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
>>>>> Just thought some might be interested in hearing our recent guest on
>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>> Magic" fame[...]
>>>
>>> Yeah, his book is half nonsense. If you can tell which half is which,
>>> you don't need the book. His ideas on "return currents" and bypassing
>>> are absurd. And the writing is dreadful.
>>
>> I haven't got the book handy, but I'll pick it up tomorrow or so.
>> Do you mind expounding on why his "return currents" make no sense?
>> Did he mean something different from image currents?
> 
> He says that a transmission-line pcb trace must always be "referenced"
> to the same "return current" plane it started with and shouldn't pass
> through vias to become referenced to a different plane, or else the
> return currents will get confused or go on strike or something. If
> that were true, 98% or the multilayer boards on Earth would quit
> working.
> 
> He also says that you should add bypass caps and stitching vias to
> conduct these return currents whenever a trace does via to a different
> "reference plane." 
> 
> All silly.

Ah, yes, I agree with you there. Mostly anyway. Capacitance between
planes should be plenty to take care of that.

I *did* have this amplifier with a ridiculously high gain that
wouldn't keep still with its output trace running over the V+
plane. The problem vanished when I made it run over a GND plane
instead. Then again, there were a few other layout tweaks that
may have contributed to fixing it.

Jeroen Belleman

On Tue, 10 Jan 2012 22:41:11 +0100, Jeroen <jeroen@nospam.please>
wrote:

>On 2012-01-10 17:50, John Larkin wrote:
>> On Tue, 10 Jan 2012 17:29:35 +0100, Jeroen Belleman
>> <jeroen@nospam.please> wrote:
>> 
>>> John Larkin wrote:
>>>> On Tue, 10 Jan 2012 01:28:22 -0800 (PST), Bill Sloman
>>>> <bill.sloman@ieee.org> wrote:
>>>>
>>>>> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>> Magic" fame[...]
>>>>
>>>> Yeah, his book is half nonsense. If you can tell which half is which,
>>>> you don't need the book. His ideas on "return currents" and bypassing
>>>> are absurd. And the writing is dreadful.
>>>
>>> I haven't got the book handy, but I'll pick it up tomorrow or so.
>>> Do you mind expounding on why his "return currents" make no sense?
>>> Did he mean something different from image currents?
>> 
>> He says that a transmission-line pcb trace must always be "referenced"
>> to the same "return current" plane it started with and shouldn't pass
>> through vias to become referenced to a different plane, or else the
>> return currents will get confused or go on strike or something. If
>> that were true, 98% or the multilayer boards on Earth would quit
>> working.
>> 
>> He also says that you should add bypass caps and stitching vias to
>> conduct these return currents whenever a trace does via to a different
>> "reference plane." 
>> 
>> All silly.
>
>Ah, yes, I agree with you there. Mostly anyway. Capacitance between
>planes should be plenty to take care of that.

Exactly. The planes are huge and essentially equipotential, so the
wavefront zooming down a trace doesn't know or care what its reference
plane originally was.

>
>I *did* have this amplifier with a ridiculously high gain that
>wouldn't keep still with its output trace running over the V+
>plane. The problem vanished when I made it run over a GND plane
>instead. Then again, there were a few other layout tweaks that
>may have contributed to fixing it.
>
>Jeroen Belleman

Noise on a power plane can certainly couple into a signal trace. And
planes can resonate and couple to things. But this "return current"
fixation is silly.

Here's a TDR test trace, bottom of page.

http://johnlarkin.yolasite.com/pc-boards.php

This is referenced to all sorts of power and ground planes.

John

On Jan 10, 5:50 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Tue, 10 Jan 2012 17:29:35 +0100, Jeroen Belleman
>
>
>
>
>
>
>
>
>
> <jer...@nospam.please> wrote:
> >John Larkin wrote:
> >> On Tue, 10 Jan 2012 01:28:22 -0800 (PST), Bill Sloman
> >> <bill.slo...@ieee.org> wrote:
>
> >>> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
> >>>> Just thought some might be interested in hearing our recent guest on
> >>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> >>>> Magic" fame[...]
>
> >> Yeah, his book is half nonsense. If you can tell which half is which,
> >> you don't need the book. His ideas on "return currents" and bypassing
> >> are absurd. And the writing is dreadful.
>
> >I haven't got the book handy, but I'll pick it up tomorrow or so.
> >Do you mind expounding on why his "return currents" make no sense?
> >Did he mean something different from image currents?
>
> He says that a transmission-line pcb trace must always be "referenced"
> to the same "return current" plane it started with and shouldn't pass
> through vias to become referenced to a different plane, or else the
> return currents will get confused or go on strike or something. If
> that were true, 98% or the multilayer boards on Earth would quit
> working.
>
> He also says that you should add bypass caps and stitching vias to
> conduct these return currents whenever a trace does via to a different
> "reference plane."
>
> All silly.

Not completely silly. One of the more avoidable hold-ups in the
development of the electron beam tester at Cambridge Instruments from
1988 to 1991 was when the drafting office sent out a six layer board
for manufacture without specifying the order of the inner planes -
they "knew" that the order didn't matter, despite the fact that I'd
spelled it out, in detail, on the release note that I'd given them.

Almost all of the very high frequency connections - from GaAs logic
outputs to GaAs logic inputs - were supposed to have been routed
directly above the -2V plane (which should have been directly under
the components), and the terminating resistors were returned to that
plane (through a via at the relevant end of the resistor).

The board didn't work, and it took us a while to find out why.
Whenever I walked past the engineer working on the board I'd remind
him that he had the stuck of images of the various planes stuck
together in the wrong order, and eventually this irritated him enough
that he got out a drill and worked that he'd got them in the right
order, which explained most of why the board wasn't working.

We did get it to work eventually, but all the high-frequency
connections through the board ended up being routed through tacked-on
lumps of sub-miniature coaxial cable.

The next board had the inner planes in the right order, amongst other
changes, and worked a lot better.

--
Bill Sloman, Nijmegen

--
Bill Sloman, Nijmegen

On Jan 11, 5:09 am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> Did you have to pay him? How much?

No, he was not paid, non of our guests are.
We invite them on and they graciously agree to give up their time to
participate.

Dave.

"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in 
message news:1vrog79stvtva2oejgqvdj9dj8qno9prdq@4ax.com...
> On Mon, 9 Jan 2012 22:47:01 -0800 (PST), "David L. Jones"
> <altzone@gmail.com> wrote:
>
>>Just thought some might be interested in hearing our recent guest on
>>our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>Magic" fame:
>>http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform-wizardry/
>>
>>Lots of history of the book, signal integrity, Gigabit Ethernet
>>development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>other talk over almost 1 1/12 hours.
>>
>>Dave.
>
> Howard Johnson?  Wasn't that a restaurant that you went to for clam
> strips ?:-)
>
>                                        ...Jim Thompson

I think there are only two HJ's left in the whole country.  I ate at the one 
in Lake Placid a few times. 

On Tue, 10 Jan 2012 15:39:08 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Jan 10, 5:50�pm, John Larkin
><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>> On Tue, 10 Jan 2012 17:29:35 +0100, Jeroen Belleman
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> <jer...@nospam.please> wrote:
>> >John Larkin wrote:
>> >> On Tue, 10 Jan 2012 01:28:22 -0800 (PST), Bill Sloman
>> >> <bill.slo...@ieee.org> wrote:
>>
>> >>> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
>> >>>> Just thought some might be interested in hearing our recent guest on
>> >>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>> >>>> Magic" fame[...]
>>
>> >> Yeah, his book is half nonsense. If you can tell which half is which,
>> >> you don't need the book. His ideas on "return currents" and bypassing
>> >> are absurd. And the writing is dreadful.
>>
>> >I haven't got the book handy, but I'll pick it up tomorrow or so.
>> >Do you mind expounding on why his "return currents" make no sense?
>> >Did he mean something different from image currents?
>>
>> He says that a transmission-line pcb trace must always be "referenced"
>> to the same "return current" plane it started with and shouldn't pass
>> through vias to become referenced to a different plane, or else the
>> return currents will get confused or go on strike or something. If
>> that were true, 98% or the multilayer boards on Earth would quit
>> working.
>>
>> He also says that you should add bypass caps and stitching vias to
>> conduct these return currents whenever a trace does via to a different
>> "reference plane."
>>
>> All silly.
>
>Not completely silly. One of the more avoidable hold-ups in the
>development of the electron beam tester at Cambridge Instruments from
>1988 to 1991 was when the drafting office sent out a six layer board
>for manufacture without specifying the order of the inner planes -
>they "knew" that the order didn't matter, despite the fact that I'd
>spelled it out, in detail, on the release note that I'd given them.
>
>Almost all of the very high frequency connections - from GaAs logic
>outputs to GaAs logic inputs - were supposed to have been routed
>directly above the -2V plane (which should have been directly under
>the components), and the terminating resistors were returned to that
>plane (through a via at the relevant end of the resistor).
>
>The board didn't work, and it took us a while to find out why.
>Whenever I walked past the engineer working on the board I'd remind
>him that he had the stuck of images of the various planes stuck
>together in the wrong order, and eventually this irritated him enough
>that he got out a drill and worked that he'd got them in the right
>order, which explained most of why the board wasn't working.
>
>We did get it to work eventually, but all the high-frequency
>connections through the board ended up being routed through tacked-on
>lumps of sub-miniature coaxial cable.
>
>The next board had the inner planes in the right order, amongst other
>changes, and worked a lot better.
>
>--
>Bill Sloman, Nijmegen


Of course the stackup and order matter, if not to get the DC
connections right, then to get the impedances right. But the obsession
with return currents and "reference planes" is mostly silly.

As is the admonition to never cross slits in planes, fr'instance
running a trace above a plane that has multiple pour pours.

John

On 1/10/2012 6:49 PM, John Larkin wrote:

> As is the admonition to never cross slits in planes, fr'instance
> running a trace above a plane that has multiple pour pours.
>
> John

Did you mean "multiple poor pours."?  :-)

On Tue, 10 Jan 2012 19:36:11 -0500, "Michael Robinson"
<kellrobinson@yahoo.com.no_spam> wrote:

>
>"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote in 
>message news:1vrog79stvtva2oejgqvdj9dj8qno9prdq@4ax.com...
>> On Mon, 9 Jan 2012 22:47:01 -0800 (PST), "David L. Jones"
>> <altzone@gmail.com> wrote:
>>
>>>Just thought some might be interested in hearing our recent guest on
>>>our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>Magic" fame:
>>>http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform-wizardry/
>>>
>>>Lots of history of the book, signal integrity, Gigabit Ethernet
>>>development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>other talk over almost 1 1/12 hours.
>>>
>>>Dave.
>>
>> Howard Johnson?  Wasn't that a restaurant that you went to for clam
>> strips ?:-)
>>
>>                                        ...Jim Thompson
>
>I think there are only two HJ's left in the whole country.  I ate at the one 
>in Lake Placid a few times. 

According to Wikipedia, there are three; Lake Placid NY, Lake George NY (I
knew I'd seen one recently), and Bangor ME.  

On Jan 10, 5:21 pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My-
Web-Site.com> wrote:
> On Tue, 10 Jan 2012 15:55:53 +0000, John Devereux
>
>
>
>
>
>
>
>
>
> <j...@devereux.me.uk> wrote:
> >Robert Macy <robert.a.m...@gmail.com> writes:
>
> >> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org> wrote:
> >>> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
>
> >>> > Just thought some might be interested in hearing our recent guest on
> >>> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> >>> > Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>
> >>> > Lots of history of the book, signal integrity, Gigabit Ethernet
> >>> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
> >>> > other talk over almost 1 1/12 hours.
>
> >>> "Black Magic" is more notorious than famous. I own both it and it's
> >>> follow-up, and both have got some useful content but they are badly
> >>> organised and what useful content they do contain is hard to find.
>
> >>> The field is still waiting for a decent textbook on high speed circuit
> >>> design and layout.
>
> >>> This is one of the few matters on which John Larkin and I seem to
> >>> agree.
>
> >>> --
> >>>BillSloman, Nijmegen
>
> >> Perhaps, it is time for the first ever 'conference' book written by a
> >> consortium of engineers/scientists.
>
> >> Put my name in for proffreading.  :)
>
> >Great idea. Perhaps John Larkin, Jim Thompson andBillSlomancould
> >collaborate on it.
>
> >Sure that will work out well... :)
>
> Yep.  I'm the only one that's armed ;-)

Pity about the brained.

--
Bill Sloman, Nijmegen

On Tue, 10 Jan 2012 17:38:43 -0800 (PST), Bill Sloman
<bill.sloman@gmail.com> wrote:

>On Jan 10, 5:21�pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My-
>Web-Site.com> wrote:
>> On Tue, 10 Jan 2012 15:55:53 +0000, John Devereux
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> <j...@devereux.me.uk> wrote:
>> >Robert Macy <robert.a.m...@gmail.com> writes:
>>
>> >> On Jan 10, 2:28�am,BillSloman<bill.slo...@ieee.org> wrote:
>> >>> On Jan 10, 7:47�am, "David L. Jones" <altz...@gmail.com> wrote:
>>
>> >>> > Just thought some might be interested in hearing our recent guest on
>> >>> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>> >>> > Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>
>> >>> > Lots of history of the book, signal integrity, Gigabit Ethernet
>> >>> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>> >>> > other talk over almost 1 1/12 hours.
>>
>> >>> "Black Magic" is more notorious than famous. I own both it and it's
>> >>> follow-up, and both have got some useful content but they are badly
>> >>> organised and what useful content they do contain is hard to find.
>>
>> >>> The field is still waiting for a decent textbook on high speed circuit
>> >>> design and layout.
>>
>> >>> This is one of the few matters on which John Larkin and I seem to
>> >>> agree.
>>
>> >>> --
>> >>>BillSloman, Nijmegen
>>
>> >> Perhaps, it is time for the first ever 'conference' book written by a
>> >> consortium of engineers/scientists.
>>
>> >> Put my name in for proffreading. �:)
>>
>> >Great idea. Perhaps John Larkin, Jim Thompson andBillSlomancould
>> >collaborate on it.
>>
>> >Sure that will work out well... :)
>>
>> Yep. �I'm the only one that's armed ;-)
>
>Pity about the brained.

His switcher design is due before midnight. Should be fun.

John

On Jan 11, 1:49 am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Tue, 10 Jan 2012 15:39:08 -0800 (PST),BillSloman
>
>
>
>
>
>
>
>
>
> <bill.slo...@ieee.org> wrote:
> >On Jan 10, 5:50 pm, John Larkin
> ><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> >> On Tue, 10 Jan 2012 17:29:35 +0100, Jeroen Belleman
>
> >> <jer...@nospam.please> wrote:
> >> >John Larkin wrote:
> >> >> On Tue, 10 Jan 2012 01:28:22 -0800 (PST),BillSloman
> >> >> <bill.slo...@ieee.org> wrote:
>
> >> >>> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
> >> >>>> Just thought some might be interested in hearing our recent guest on
> >> >>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> >> >>>> Magic" fame[...]

<snip>

> >Not completely silly. One of the more avoidable hold-ups in the
> >development of the electron beam tester at Cambridge Instruments from
> >1988 to 1991 was when the drafting office sent out a six layer board
> >for manufacture without specifying the order of the inner planes -
> >they "knew" that the order didn't matter, despite the fact that I'd
> >spelled it out, in detail, on the release note that I'd given them.
>
> >Almost all of the very high frequency connections - from GaAs logic
> >outputs to GaAs logic inputs - were supposed to have been routed
> >directly above the -2V plane (which should have been directly under
> >the components), and the terminating resistors were returned to that
> >plane (through a via at the relevant end of the resistor).
>
> >The board didn't work, and it took us a while to find out why.
> >Whenever I walked past the engineer working on the board I'd remind
> >him that he had the stuck of images of the various planes stuck
> >together in the wrong order, and eventually this irritated him enough
> >that he got out a drill and worked that he'd got them in the right
> >order, which explained most of why the board wasn't working.
>
> >We did get it to work eventually, but all the high-frequency
> >connections through the board ended up being routed through tacked-on
> >lumps of sub-miniature coaxial cable.
>
> >The next board had the inner planes in the right order, amongst other
> >changes, and worked a lot better.

> Of course the stackup and order matter, if not to get the DC
> connections right,

Our suppliers back then didn't do buried vias, and the boards weren't
so tightly packed that we had any need of them, so the DC connections
were going to be fine, independent of the stack-up, but the return
current under the transmission-line tracks did end up following rather
more convoluted routes than we'd had in mind.

> then to get the impedances right. But the obsession
> with return currents and "reference planes" is mostly silly.

Return current routing does matter, and you should keep it in mind.
Half-baked rules of thumb aren't a good substitute for thinking about
what is going on, but thye can be better than nothing.

> As is the admonition to never cross slits in planes, fr'instance
> running a trace above a plane that has multiple pour pours.

It certainly changes the transmission line impedance in the vicinity
of the slit, if the slit is long enough vis a vis the transition time
of the edge travelling along the transmission line.

--
Bill Sloman, Nijmegen

On Tue, 10 Jan 2012 17:46:03 -0800, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

>On Tue, 10 Jan 2012 17:38:43 -0800 (PST), Bill Sloman
><bill.sloman@gmail.com> wrote:
>
>>On Jan 10, 5:21�pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My-
>>Web-Site.com> wrote:
>>> On Tue, 10 Jan 2012 15:55:53 +0000, John Devereux
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> <j...@devereux.me.uk> wrote:
>>> >Robert Macy <robert.a.m...@gmail.com> writes:
>>>
>>> >> On Jan 10, 2:28�am,BillSloman<bill.slo...@ieee.org> wrote:
>>> >>> On Jan 10, 7:47�am, "David L. Jones" <altz...@gmail.com> wrote:
>>>
>>> >>> > Just thought some might be interested in hearing our recent guest on
>>> >>> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>> >>> > Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>>
>>> >>> > Lots of history of the book, signal integrity, Gigabit Ethernet
>>> >>> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>> >>> > other talk over almost 1 1/12 hours.
>>>
>>> >>> "Black Magic" is more notorious than famous. I own both it and it's
>>> >>> follow-up, and both have got some useful content but they are badly
>>> >>> organised and what useful content they do contain is hard to find.
>>>
>>> >>> The field is still waiting for a decent textbook on high speed circuit
>>> >>> design and layout.
>>>
>>> >>> This is one of the few matters on which John Larkin and I seem to
>>> >>> agree.
>>>
>>> >>> --
>>> >>>BillSloman, Nijmegen
>>>
>>> >> Perhaps, it is time for the first ever 'conference' book written by a
>>> >> consortium of engineers/scientists.
>>>
>>> >> Put my name in for proffreading. �:)
>>>
>>> >Great idea. Perhaps John Larkin, Jim Thompson andBillSlomancould
>>> >collaborate on it.
>>>
>>> >Sure that will work out well... :)
>>>
>>> Yep. �I'm the only one that's armed ;-)
>>
>>Pity about the brained.
>
>His switcher design is due before midnight. Should be fun.
>
>John

John Are you really that ignorant/narcissistic?  You know that what I
post will work.  Why don't you knock off the crap and grow up?  Or are
you intent in going down in history as just another Slowman...
worthless and limp-dicked by the time you reach "old age" ?:-)
		
                                        ...Jim Thompson
-- 
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

On Tue, 10 Jan 2012 18:56:35 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

>On Tue, 10 Jan 2012 17:46:03 -0800, John Larkin
><jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:
>
>>On Tue, 10 Jan 2012 17:38:43 -0800 (PST), Bill Sloman
>><bill.sloman@gmail.com> wrote:
>>
>>>On Jan 10, 5:21�pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My-
>>>Web-Site.com> wrote:
>>>> On Tue, 10 Jan 2012 15:55:53 +0000, John Devereux
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> <j...@devereux.me.uk> wrote:
>>>> >Robert Macy <robert.a.m...@gmail.com> writes:
>>>>
>>>> >> On Jan 10, 2:28�am,BillSloman<bill.slo...@ieee.org> wrote:
>>>> >>> On Jan 10, 7:47�am, "David L. Jones" <altz...@gmail.com> wrote:
>>>>
>>>> >>> > Just thought some might be interested in hearing our recent guest on
>>>> >>> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>> >>> > Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>>>
>>>> >>> > Lots of history of the book, signal integrity, Gigabit Ethernet
>>>> >>> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>> >>> > other talk over almost 1 1/12 hours.
>>>>
>>>> >>> "Black Magic" is more notorious than famous. I own both it and it's
>>>> >>> follow-up, and both have got some useful content but they are badly
>>>> >>> organised and what useful content they do contain is hard to find.
>>>>
>>>> >>> The field is still waiting for a decent textbook on high speed circuit
>>>> >>> design and layout.
>>>>
>>>> >>> This is one of the few matters on which John Larkin and I seem to
>>>> >>> agree.
>>>>
>>>> >>> --
>>>> >>>BillSloman, Nijmegen
>>>>
>>>> >> Perhaps, it is time for the first ever 'conference' book written by a
>>>> >> consortium of engineers/scientists.
>>>>
>>>> >> Put my name in for proffreading. �:)
>>>>
>>>> >Great idea. Perhaps John Larkin, Jim Thompson andBillSlomancould
>>>> >collaborate on it.
>>>>
>>>> >Sure that will work out well... :)
>>>>
>>>> Yep. �I'm the only one that's armed ;-)
>>>
>>>Pity about the brained.
>>
>>His switcher design is due before midnight. Should be fun.
>>
>>John
>
>John Are you really that ignorant/narcissistic?  You know that what I
>post will work. 

Post it and we'll see.

John

On Jan 10, 4:55 pm, John Devereux <j...@devereux.me.uk> wrote:
> Robert Macy <robert.a.m...@gmail.com> writes:
> > On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org> wrote:
> >> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
>
> >> > Just thought some might be interested in hearing our recent guest on
> >> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> >> > Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>
> >> > Lots of history of the book, signal integrity, Gigabit Ethernet
> >> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
> >> > other talk over almost 1 1/12 hours.
>
> >> "Black Magic" is more notorious than famous. I own both it and it's
> >> follow-up, and both have got some useful content but they are badly
> >> organised and what useful content they do contain is hard to find.
>
> >> The field is still waiting for a decent textbook on high speed circuit
> >> design and layout.
>
> >> This is one of the few matters on which John Larkin and I seem to
> >> agree.
>
> >> --
> >>BillSloman, Nijmegen
>
> > Perhaps, it is time for the first ever 'conference' book written by a
> > consortium of engineers/scientists.
>
> > Put my name in for proffreading.  :)
>
> Great idea. Perhaps John Larkin, Jim Thompson and Bill Sloman could
> collaborate on it.
>
> Sure that will work out well... :)

I'm not sure what Jim Thompson might contribute. I've seen papers that
worry about the characteristic impedance of connections on the silicon
(or whatever) inside integrated circuits, but I don't have the feeling
that Jim designs stuff that's big enough and fast enough for him to
need to know much about it.

Motorola's ECL applications notes on board layout were rather useful,
and date back to Jim's time with them, but he won't have written them,
any more than he wrote the rather comprehensive applications notes for
his MC4024/MC4044 precursors of the 4046, though he may have
supervised the people who did.

--
Bill Sloman, Nijmegen

On Jan 11, 1:06 am, "David L. Jones" <altz...@gmail.com> wrote:
> On Jan 11, 5:09 am, John Larkin
>
> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> > Did you have to pay him? How much?
>
> No, he was not paid, non of our guests are.
> We invite them on and they graciously agree to give up their time to
> participate.

Rather like authors going on "signing tours" to get a bit more
publicity for the books they have written.

Winfield Hill never seems to have done that in the past. Maybe he'll
get sent on tour when the third edition finally comes off the press.

--
Bill Sloman, Nijmegen

On Jan 10, 12:09 pm, Phil Hobbs
<pcdhSpamMeSensel...@electrooptical.net> wrote:
> On 01/10/2012 01:47 AM, David L. Jones wrote:
>
> > Just thought some might be interested in hearing our recent guest on
> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> > Magic" fame:
> >http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>
> > Lots of history of the book, signal integrity, Gigabit Ethernet
> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
> > other talk over almost 1 1/12 hours.
>
> > Dave.
>
> HJ has a mixture of good stuff and complete nonsense.
>
> I hope you grilled him a bit about his less sensible stuff, like that
> hilariously erroneous video where he attempts to use electrostatics to
> demonstrate that ground currents want to flow under traces.  Of course,
> the impedance levels are millions of times too high for inductance to be
> a factor in that demo, but never mind.    Have a look athttp://www.sigcon.com/Pubs/news/8_08.htmfor the whole ridiculous thing.
>
> (The current path is determined by corona discharge at the sharp corners
> of the metal squares--if you look at all closely, you'll see that the
> discharges always want to go out the corners of the squares.)
>
> Cheers
>
> Phil Hobbs
>
> --
> Dr Philip C D Hobbs
> Principal Consultant
> ElectroOptical Innovations LLC
> Optics, Electro-optics, Photonics, Analog Electronics
>
> 160 North State Road #203
> Briarcliff Manor NY 10510
> 845-480-2058
>
> hobbs at electrooptical dot nethttp://electrooptical.net

That is pretty silly.
But certainly it's a good idea to keep a nice unbroken ground plane
under the signal(s) that you really care about.

George H.

On 01/10/2012 09:27 PM, George Herold wrote:
> On Jan 10, 12:09 pm, Phil Hobbs
> <pcdhSpamMeSensel...@electrooptical.net>  wrote:
>> On 01/10/2012 01:47 AM, David L. Jones wrote:
>>
>>> Just thought some might be interested in hearing our recent guest on
>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>> Magic" fame:
>>> http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>
>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>> other talk over almost 1 1/12 hours.
>>
>>> Dave.
>>
>> HJ has a mixture of good stuff and complete nonsense.
>>
>> I hope you grilled him a bit about his less sensible stuff, like that
>> hilariously erroneous video where he attempts to use electrostatics to
>> demonstrate that ground currents want to flow under traces.  Of course,
>> the impedance levels are millions of times too high for inductance to be
>> a factor in that demo, but never mind.    Have a look athttp://www.sigcon.com/Pubs/news/8_08.htmfor the whole ridiculous thing.
>>
>> (The current path is determined by corona discharge at the sharp corners
>> of the metal squares--if you look at all closely, you'll see that the
>> discharges always want to go out the corners of the squares.)
>>
>> Cheers
>>
>> Phil Hobbs

>
> That is pretty silly.
> But certainly it's a good idea to keep a nice unbroken ground plane
> under the signal(s) that you really care about.
>
> George H.

I don't disagree with you there.  But I have small respect for someone 
who makes his living peddling that sort of cargo-cult stuff.  If he ever 
corrected himself, or offered actual real-world data or simulations, I'd 
pay attention.  As it is, his stuff is like an old time medicine 
show--the willow bark tea works, the snake oil doesn't, no apparent 
effort is expended to sort them out.

Remember the little boy in the story:  "Why do you keep snapping your 
fingers, Bobby?" "To keep polar bears away."  "But there isn't a polar 
bear within 2000 miles of here!"  "Works great, doesn't it?"

Read Morrison instead.

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

On Tue, 10 Jan 2012 18:27:01 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

>On Jan 10, 12:09�pm, Phil Hobbs
><pcdhSpamMeSensel...@electrooptical.net> wrote:
>> On 01/10/2012 01:47 AM, David L. Jones wrote:
>>
>> > Just thought some might be interested in hearing our recent guest on
>> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>> > Magic" fame:
>> >http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>
>> > Lots of history of the book, signal integrity, Gigabit Ethernet
>> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>> > other talk over almost 1 1/12 hours.
>>
>> > Dave.
>>
>> HJ has a mixture of good stuff and complete nonsense.
>>
>> I hope you grilled him a bit about his less sensible stuff, like that
>> hilariously erroneous video where he attempts to use electrostatics to
>> demonstrate that ground currents want to flow under traces. �Of course,
>> the impedance levels are millions of times too high for inductance to be
>> a factor in that demo, but never mind. � �Have a look athttp://www.sigcon.com/Pubs/news/8_08.htmfor the whole ridiculous thing.
>>
>> (The current path is determined by corona discharge at the sharp corners
>> of the metal squares--if you look at all closely, you'll see that the
>> discharges always want to go out the corners of the squares.)
>>
>> Cheers
>>
>> Phil Hobbs
>>
>> --
>> Dr Philip C D Hobbs
>> Principal Consultant
>> ElectroOptical Innovations LLC
>> Optics, Electro-optics, Photonics, Analog Electronics
>>
>> 160 North State Road #203
>> Briarcliff Manor NY 10510
>> 845-480-2058
>>
>> hobbs at electrooptical dot nethttp://electrooptical.net
>
>That is pretty silly.
>But certainly it's a good idea to keep a nice unbroken ground plane
>under the signal(s) that you really care about.
>
>George H.

That's often not practical. If the issue is a digital logic signal
cruising above a layer that has multiple power pours, with
design-rule-sized gaps between them, it's not likely to be a problem.
The power pours are big slabs of copper with a lot of capacitance to
the ground plane and to the universe, and are generally bypassed, so
as far as the signal trace is concerned, they may as well be over
ground. And a wavefront, even a 100 ps one, is not going to be much
disturbed by cruising over a narrow gap in the copper; it is filled
with epoxy. I've built test boards with this geometry, and with
deliberate slits in ground planes, and I've measured this stuff.

One day I should lay out a horrible-example multilayer board and
document what really happens. I do often put test traces on production
boards, to see how we're doing on the impedance calculations.

http://johnlarkin.yolasite.com/pc-boards.php


John

On Jan 11, 4:08 am, Bill Sloman <bill.slo...@gmail.com> wrote:
> On Jan 11, 1:06 am, "David L. Jones" <altz...@gmail.com> wrote:
>
> > On Jan 11, 5:09 am, John Larkin
>
> > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> > > Did you have to pay him? How much?
>
> > No, he was not paid, non of our guests are.
> > We invite them on and they graciously agree to give up their time to
> > participate.
>
> Rather like authors going on "signing tours" to get a bit more
> publicity for the books they have written.

No, not at all.
We liked him so invited him on the show, he did not approach us.
He was kind enough to come on and be a guest without any agenda at
all.

Dave.

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in 
message news:a6qog71oeiacboqnku38gr0qq7tnf4njfc@4ax.com...
> He says that a transmission-line pcb trace must always be "referenced"
> to the same "return current" plane it started with and shouldn't pass
> through vias to become referenced to a different plane, or else the
> return currents will get confused or go on strike or something. If
> that were true, 98% or the multilayer boards on Earth would quit
> working.
>
> He also says that you should add bypass caps and stitching vias to
> conduct these return currents whenever a trace does via to a different
> "reference plane."
>
> All silly.

You're just spoiled...

8-layer boards aren't cheap.  Heck, four layer boards aren't cheap.  If I 
can avoid it, I'll pick 2 layer whenever possible.  Great proto prices and 
turn arounds.  With two layers to choose from, you have no choice but to 
stitch like a carpet.  You only have room for one ground plane as such. 
Heck, if you think you have room for two (maybe VCC and GND), you're being 
lazy and could get by with 1 layer. :)

Tim

-- 
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms 

On Tue, 10 Jan 2012 21:10:15 -0600, "Tim Williams"
<tmoranwms@charter.net> wrote:

>"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in 
>message news:a6qog71oeiacboqnku38gr0qq7tnf4njfc@4ax.com...
>> He says that a transmission-line pcb trace must always be "referenced"
>> to the same "return current" plane it started with and shouldn't pass
>> through vias to become referenced to a different plane, or else the
>> return currents will get confused or go on strike or something. If
>> that were true, 98% or the multilayer boards on Earth would quit
>> working.
>>
>> He also says that you should add bypass caps and stitching vias to
>> conduct these return currents whenever a trace does via to a different
>> "reference plane."
>>
>> All silly.
>
>You're just spoiled...
>
>8-layer boards aren't cheap.  Heck, four layer boards aren't cheap.  If I 
>can avoid it, I'll pick 2 layer whenever possible.  Great proto prices and 
>turn arounds.  With two layers to choose from, you have no choice but to 
>stitch like a carpet.  You only have room for one ground plane as such. 
>Heck, if you think you have room for two (maybe VCC and GND), you're being 
>lazy and could get by with 1 layer. :)
>
>Tim


8's do get expensive, and you can't do serious stuff on 4, so we try
to use 6 layers when we can. Routing a BGA FPGA to a BGA ARM and then
to a lot of ADCs and such can be a challenge on 6 layers. 

Having a solid ground layer is great for signal integrity, mandatory
for fast stuff. And the power pours make nice heat sinks for voltage
regulators and power opamps and things.

I haven't done a single-sided board in decades. We do do some doubles
for adapters and breakouts, things like that.

But a bare board, 6 or 8 layers, is a per cent or two of our selling
price. It makes more sense to pack on features and sell a few more.

John

On Tue, 10 Jan 2012 21:10:15 -0600, the renowned "Tim Williams"
<tmoranwms@charter.net> wrote:

>
>You're just spoiled...
>
>8-layer boards aren't cheap.  Heck, four layer boards aren't cheap.  If I 
>can avoid it, I'll pick 2 layer whenever possible.  Great proto prices and 
>turn arounds.  With two layers to choose from, you have no choice but to 
>stitch like a carpet.  You only have room for one ground plane as such. 
>Heck, if you think you have room for two (maybe VCC and GND), you're being 
>lazy and could get by with 1 layer. :)
>
>Tim

These days even a house thermostat design requires a 432 pin BGA (plus
scores of other parts), so 1 or 2 layer boards are not practical. 8-(


Best regards, 
Spehro Pefhany
-- 
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

<krw@att.bizzzzzzzzzzzz> wrote in message 
news:ssnpg79a6ro6vsa8fji578jtdhq10aldph@4ax.com...
> On Tue, 10 Jan 2012 19:36:11 -0500, "Michael Robinson"
> <kellrobinson@yahoo.com.no_spam> wrote:
>
>>
>>"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote 
>>in
>>message news:1vrog79stvtva2oejgqvdj9dj8qno9prdq@4ax.com...
>>> On Mon, 9 Jan 2012 22:47:01 -0800 (PST), "David L. Jones"
>>> <altzone@gmail.com> wrote:
>>>
>>>>Just thought some might be interested in hearing our recent guest on
>>>>our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>Magic" fame:
>>>>http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform-wizardry/
>>>>
>>>>Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>other talk over almost 1 1/12 hours.
>>>>
>>>>Dave.
>>>
>>> Howard Johnson?  Wasn't that a restaurant that you went to for clam
>>> strips ?:-)
>>>
>>>                                        ...Jim Thompson
>>
>>I think there are only two HJ's left in the whole country.  I ate at the 
>>one
>>in Lake Placid a few times.
>
> According to Wikipedia, there are three; Lake Placid NY, Lake George NY (I
> knew I'd seen one recently), and Bangor ME.
>
I stand corrected. 

John Larkin wrote:
> On Tue, 10 Jan 2012 15:39:08 -0800 (PST), Bill Sloman
> <bill.sloman@ieee.org> wrote:
> 
>> On Jan 10, 5:50 pm, John Larkin
>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>>> On Tue, 10 Jan 2012 17:29:35 +0100, Jeroen Belleman
>>> <jer...@nospam.please> wrote:
>>>> John Larkin wrote:
>>>>> On Tue, 10 Jan 2012 01:28:22 -0800 (PST), Bill Sloman
>>>>> <bill.slo...@ieee.org> wrote:
>>>>>> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
>>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>>> Magic" fame[...]
>>>>> Yeah, his book is half nonsense. If you can tell which half is which,
>>>>> you don't need the book. His ideas on "return currents" and bypassing
>>>>> are absurd. And the writing is dreadful.
>>>> I haven't got the book handy, but I'll pick it up tomorrow or so.
>>>> Do you mind expounding on why his "return currents" make no sense?
>>>> Did he mean something different from image currents?
>>> He says that a transmission-line pcb trace must always be "referenced"
>>> to the same "return current" plane it started with and shouldn't pass
>>> through vias to become referenced to a different plane, or else the
>>> return currents will get confused or go on strike or something. If
>>> that were true, 98% or the multilayer boards on Earth would quit
>>> working.
>>>
>>> He also says that you should add bypass caps and stitching vias to
>>> conduct these return currents whenever a trace does via to a different
>>> "reference plane."
>>>
>>> All silly.
>> Not completely silly. One of the more avoidable hold-ups in the
>> development of the electron beam tester at Cambridge Instruments from
>> 1988 to 1991 was when the drafting office sent out a six layer board
>> for manufacture without specifying the order of the inner planes -[...]
>> The next board had the inner planes in the right order, amongst other
>> changes, and worked a lot better.
>>
>> --
>> Bill Sloman, Nijmegen
> 
> 
> Of course the stackup and order matter, if not to get the DC
> connections right, then to get the impedances right. But the obsession
> with return currents and "reference planes" is mostly silly.
> 
> As is the admonition to never cross slits in planes, fr'instance
> running a trace above a plane that has multiple pour pours.
> 
> John

A track across a slit is an antenna. Unless there's another plane
underneath covering the slit, in which case it probably doesn't
matter.

Jeroen Belleman

On Jan 11, 4:04 am, "David L. Jones" <altz...@gmail.com> wrote:
> On Jan 11, 4:08 am,BillSloman<bill.slo...@gmail.com> wrote:
>
> > On Jan 11, 1:06 am, "David L. Jones" <altz...@gmail.com> wrote:
>
> > > On Jan 11, 5:09 am, John Larkin
>
> > > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> > > > Did you have to pay him? How much?
>
> > > No, he was not paid, non of our guests are.
> > > We invite them on and they graciously agree to give up their time to
> > > participate.
>
> > Rather like authors going on "signing tours" to get a bit more
> > publicity for the books they have written.
>
> No, not at all.
> We liked him so invited him on the show, he did not approach us.
> He was kind enough to come on and be a guest without any agenda at
> all.

Lucky him. There can't be all that many hosts who don't know how
marginal his stuff actually is. Rather like Michelin's lowest grade of
approval - useful in the area, at the price. His books aren't cheap,
but they are cheaper than a google search or a couple of hours in a
good technical library.

--
Bill Sloman, Nijmegen

On Wed, 11 Jan 2012 02:25:01 -0500, "Michael Robinson"
<kellrobinson@yahoo.com.no_spam> wrote:

>
><krw@att.bizzzzzzzzzzzz> wrote in message 
>news:ssnpg79a6ro6vsa8fji578jtdhq10aldph@4ax.com...
>> On Tue, 10 Jan 2012 19:36:11 -0500, "Michael Robinson"
>> <kellrobinson@yahoo.com.no_spam> wrote:
>>
>>>
>>>"Jim Thompson" <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote 
>>>in
>>>message news:1vrog79stvtva2oejgqvdj9dj8qno9prdq@4ax.com...
>>>> On Mon, 9 Jan 2012 22:47:01 -0800 (PST), "David L. Jones"
>>>> <altzone@gmail.com> wrote:
>>>>
>>>>>Just thought some might be interested in hearing our recent guest on
>>>>>our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>Magic" fame:
>>>>>http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform-wizardry/
>>>>>
>>>>>Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>>development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>>other talk over almost 1 1/12 hours.
>>>>>
>>>>>Dave.
>>>>
>>>> Howard Johnson?  Wasn't that a restaurant that you went to for clam
>>>> strips ?:-)
>>>>
>>>>                                        ...Jim Thompson
>>>
>>>I think there are only two HJ's left in the whole country.  I ate at the 
>>>one
>>>in Lake Placid a few times.
>>
>> According to Wikipedia, there are three; Lake Placid NY, Lake George NY (I
>> knew I'd seen one recently), and Bangor ME.
>>
>I stand corrected. 

Actually, I was the one who was wrong.  Having just seen one recently, I
didn't think they were down to just a few fingers.  After checking (there is a
lesson here for AlwaysWrong, but he's too dim), you were right, give or take.

On Jan 10, 9:47 pm, Phil Hobbs
<pcdhSpamMeSensel...@electrooptical.net> wrote:
> On 01/10/2012 09:27 PM, George Herold wrote:
>
>
>
>
>
> > On Jan 10, 12:09 pm, Phil Hobbs
> > <pcdhSpamMeSensel...@electrooptical.net>  wrote:
> >> On 01/10/2012 01:47 AM, David L. Jones wrote:
>
> >>> Just thought some might be interested in hearing our recent guest on
> >>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> >>> Magic" fame:
> >>>http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>
> >>> Lots of history of the book, signal integrity, Gigabit Ethernet
> >>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
> >>> other talk over almost 1 1/12 hours.
>
> >>> Dave.
>
> >> HJ has a mixture of good stuff and complete nonsense.
>
> >> I hope you grilled him a bit about his less sensible stuff, like that
> >> hilariously erroneous video where he attempts to use electrostatics to
> >> demonstrate that ground currents want to flow under traces.  Of course,
> >> the impedance levels are millions of times too high for inductance to be
> >> a factor in that demo, but never mind.    Have a look athttp://www.sigcon.com/Pubs/news/8_08.htmforthe whole ridiculous thing.
>
> >> (The current path is determined by corona discharge at the sharp corners
> >> of the metal squares--if you look at all closely, you'll see that the
> >> discharges always want to go out the corners of the squares.)
>
> >> Cheers
>
> >> Phil Hobbs
>
> > That is pretty silly.
> > But certainly it's a good idea to keep a nice unbroken ground plane
> > under the signal(s) that you really care about.
>
> > George H.
>
> I don't disagree with you there.  But I have small respect for someone
> who makes his living peddling that sort of cargo-cult stuff.  If he ever
> corrected himself, or offered actual real-world data or simulations, I'd
> pay attention.  As it is, his stuff is like an old time medicine
> show--the willow bark tea works, the snake oil doesn't, no apparent
> effort is expended to sort them out.
>
> Remember the little boy in the story:  "Why do you keep snapping your
> fingers, Bobby?" "To keep polar bears away."  "But there isn't a polar
> bear within 2000 miles of here!"  "Works great, doesn't it?"

Grin,  I've never read any of Ho Jo's books.  I figured I don't know
enough to separate the chaff from the grain.
>
> Read Morrison instead.

? Ralph Morrison on Grounding and sheilding?  (the only Morrison on my
shelf) Or someone else?

George H.
>
> Cheers
>
> Phil Hobbs
>
> --
> Dr Philip C D Hobbs
> Principal Consultant
> ElectroOptical Innovations LLC
> Optics, Electro-optics, Photonics, Analog Electronics
>
> 160 North State Road #203
> Briarcliff Manor NY 10510
> 845-480-2058
>
> hobbs at electrooptical dot nethttp://electrooptical.net- Hide quoted text -
>
> - Show quoted text -

On Jan 10, 9:48 pm, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Tue, 10 Jan 2012 18:27:01 -0800 (PST), George Herold
>
>
>
>
>
> <gher...@teachspin.com> wrote:
> >On Jan 10, 12:09 pm, Phil Hobbs
> ><pcdhSpamMeSensel...@electrooptical.net> wrote:
> >> On 01/10/2012 01:47 AM, David L. Jones wrote:
>
> >> > Just thought some might be interested in hearing our recent guest on
> >> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> >> > Magic" fame:
> >> >http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>
> >> > Lots of history of the book, signal integrity, Gigabit Ethernet
> >> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
> >> > other talk over almost 1 1/12 hours.
>
> >> > Dave.
>
> >> HJ has a mixture of good stuff and complete nonsense.
>
> >> I hope you grilled him a bit about his less sensible stuff, like that
> >> hilariously erroneous video where he attempts to use electrostatics to
> >> demonstrate that ground currents want to flow under traces. Of course,
> >> the impedance levels are millions of times too high for inductance to be
> >> a factor in that demo, but never mind. Have a look athttp://www.sigcon.com/Pubs/news/8_08.htmforthe whole ridiculous thing.
>
> >> (The current path is determined by corona discharge at the sharp corners
> >> of the metal squares--if you look at all closely, you'll see that the
> >> discharges always want to go out the corners of the squares.)
>
> >> Cheers
>
> >> Phil Hobbs
>
> >> --
> >> Dr Philip C D Hobbs
> >> Principal Consultant
> >> ElectroOptical Innovations LLC
> >> Optics, Electro-optics, Photonics, Analog Electronics
>
> >> 160 North State Road #203
> >> Briarcliff Manor NY 10510
> >> 845-480-2058
>
> >> hobbs at electrooptical dot nethttp://electrooptical.net
>
> >That is pretty silly.
> >But certainly it's a good idea to keep a nice unbroken ground plane
> >under the signal(s) that you really care about.
>
> >George H.
>
> That's often not practical. If the issue is a digital logic signal
> cruising above a layer that has multiple power pours, with
> design-rule-sized gaps between them, it's not likely to be a problem.
> The power pours are big slabs of copper with a lot of capacitance to
> the ground plane and to the universe, and are generally bypassed, so
> as far as the signal trace is concerned, they may as well be over
> ground.

Sure, the power supply is as good as ground for all but the lowest
frequencies.


And a wavefront, even a 100 ps one, is not going to be much
> disturbed by cruising over a narrow gap in the copper; it is filled
> with epoxy. I've built test boards with this geometry, and with
> deliberate slits in ground planes, and I've measured this stuff.

Hmm, You've got tons more experience than me.  But there is an
appealing logic to the slit idea... course I'm more than willing to
abandon false ideas.

>
> One day I should lay out a horrible-example multilayer board and
> document what really happens. I do often put test traces on production
> boards, to see how we're doing on the impedance calculations.

Yeah if you ever get some real data that would be wonderful.

Muller's theorm #1.  If it happens, it must be possible.
http://www.muller.lbl.gov/pages/Muller-theorems.htm

>
> http://johnlarkin.yolasite.com/pc-boards.php

Yup, I was poking around your new website last night.

George H.
>
> John- Hide quoted text -
>
> - Show quoted text -

On Wed, 11 Jan 2012 08:30:48 +0100, Jeroen Belleman
<jeroen@nospam.please> wrote:

>John Larkin wrote:
>> On Tue, 10 Jan 2012 15:39:08 -0800 (PST), Bill Sloman
>> <bill.sloman@ieee.org> wrote:
>> 
>>> On Jan 10, 5:50 pm, John Larkin
>>> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>>>> On Tue, 10 Jan 2012 17:29:35 +0100, Jeroen Belleman
>>>> <jer...@nospam.please> wrote:
>>>>> John Larkin wrote:
>>>>>> On Tue, 10 Jan 2012 01:28:22 -0800 (PST), Bill Sloman
>>>>>> <bill.slo...@ieee.org> wrote:
>>>>>>> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
>>>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>>>> Magic" fame[...]
>>>>>> Yeah, his book is half nonsense. If you can tell which half is which,
>>>>>> you don't need the book. His ideas on "return currents" and bypassing
>>>>>> are absurd. And the writing is dreadful.
>>>>> I haven't got the book handy, but I'll pick it up tomorrow or so.
>>>>> Do you mind expounding on why his "return currents" make no sense?
>>>>> Did he mean something different from image currents?
>>>> He says that a transmission-line pcb trace must always be "referenced"
>>>> to the same "return current" plane it started with and shouldn't pass
>>>> through vias to become referenced to a different plane, or else the
>>>> return currents will get confused or go on strike or something. If
>>>> that were true, 98% or the multilayer boards on Earth would quit
>>>> working.
>>>>
>>>> He also says that you should add bypass caps and stitching vias to
>>>> conduct these return currents whenever a trace does via to a different
>>>> "reference plane."
>>>>
>>>> All silly.
>>> Not completely silly. One of the more avoidable hold-ups in the
>>> development of the electron beam tester at Cambridge Instruments from
>>> 1988 to 1991 was when the drafting office sent out a six layer board
>>> for manufacture without specifying the order of the inner planes -[...]
>>> The next board had the inner planes in the right order, amongst other
>>> changes, and worked a lot better.
>>>
>>> --
>>> Bill Sloman, Nijmegen
>> 
>> 
>> Of course the stackup and order matter, if not to get the DC
>> connections right, then to get the impedances right. But the obsession
>> with return currents and "reference planes" is mostly silly.
>> 
>> As is the admonition to never cross slits in planes, fr'instance
>> running a trace above a plane that has multiple pour pours.
>> 
>> John
>
>A track across a slit is an antenna. Unless there's another plane
>underneath covering the slit, in which case it probably doesn't
>matter.

On a multilyer board, there usually is. But I've done test slits on
microstrips on 2-sided boards, clear across the board, and not much
happens. I didn't measure radiated EMI, but signal integrity wasn't
much affected at 30 ps risetimes.

John

On Wed, 11 Jan 2012 06:49:45 -0800 (PST), George Herold
<gherold@teachspin.com> wrote:

>On Jan 10, 9:48�pm, John Larkin
><jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>> On Tue, 10 Jan 2012 18:27:01 -0800 (PST), George Herold
>>
>>
>>
>>
>>
>> <gher...@teachspin.com> wrote:
>> >On Jan 10, 12:09 pm, Phil Hobbs
>> ><pcdhSpamMeSensel...@electrooptical.net> wrote:
>> >> On 01/10/2012 01:47 AM, David L. Jones wrote:
>>
>> >> > Just thought some might be interested in hearing our recent guest on
>> >> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>> >> > Magic" fame:
>> >> >http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>
>> >> > Lots of history of the book, signal integrity, Gigabit Ethernet
>> >> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>> >> > other talk over almost 1 1/12 hours.
>>
>> >> > Dave.
>>
>> >> HJ has a mixture of good stuff and complete nonsense.
>>
>> >> I hope you grilled him a bit about his less sensible stuff, like that
>> >> hilariously erroneous video where he attempts to use electrostatics to
>> >> demonstrate that ground currents want to flow under traces. Of course,
>> >> the impedance levels are millions of times too high for inductance to be
>> >> a factor in that demo, but never mind. Have a look athttp://www.sigcon.com/Pubs/news/8_08.htmforthe whole ridiculous thing.
>>
>> >> (The current path is determined by corona discharge at the sharp corners
>> >> of the metal squares--if you look at all closely, you'll see that the
>> >> discharges always want to go out the corners of the squares.)
>>
>> >> Cheers
>>
>> >> Phil Hobbs
>>
>> >> --
>> >> Dr Philip C D Hobbs
>> >> Principal Consultant
>> >> ElectroOptical Innovations LLC
>> >> Optics, Electro-optics, Photonics, Analog Electronics
>>
>> >> 160 North State Road #203
>> >> Briarcliff Manor NY 10510
>> >> 845-480-2058
>>
>> >> hobbs at electrooptical dot nethttp://electrooptical.net
>>
>> >That is pretty silly.
>> >But certainly it's a good idea to keep a nice unbroken ground plane
>> >under the signal(s) that you really care about.
>>
>> >George H.
>>
>> That's often not practical. If the issue is a digital logic signal
>> cruising above a layer that has multiple power pours, with
>> design-rule-sized gaps between them, it's not likely to be a problem.
>> The power pours are big slabs of copper with a lot of capacitance to
>> the ground plane and to the universe, and are generally bypassed, so
>> as far as the signal trace is concerned, they may as well be over
>> ground.
>
>Sure, the power supply is as good as ground for all but the lowest
>frequencies.
>
>
>And a wavefront, even a 100 ps one, is not going to be much
>> disturbed by cruising over a narrow gap in the copper; it is filled
>> with epoxy. I've built test boards with this geometry, and with
>> deliberate slits in ground planes, and I've measured this stuff.
>
>Hmm, You've got tons more experience than me.  But there is an
>appealing logic to the slit idea... course I'm more than willing to
>abandon false ideas.
>
>>
>> One day I should lay out a horrible-example multilayer board and
>> document what really happens. I do often put test traces on production
>> boards, to see how we're doing on the impedance calculations.
>
>Yeah if you ever get some real data that would be wonderful.
>
>Muller's theorm #1.  If it happens, it must be possible.
>http://www.muller.lbl.gov/pages/Muller-theorems.htm
>
>>
>> http://johnlarkin.yolasite.com/pc-boards.php
>
>Yup, I was poking around your new website last night.

I'm just fooling around, getting a feel for it. I've got to figure out
how to organize sub-pages, or upgrade to the paid version that does
that stuff better.

And I need a section for political and economic rants.

John

On 01/11/2012 09:36 AM, George Herold wrote:
> On Jan 10, 9:47 pm, Phil Hobbs
> <pcdhSpamMeSensel...@electrooptical.net>  wrote:
>> On 01/10/2012 09:27 PM, George Herold wrote:
>>
>>
>>
>>
>>
>>> On Jan 10, 12:09 pm, Phil Hobbs
>>> <pcdhSpamMeSensel...@electrooptical.net>    wrote:
>>>> On 01/10/2012 01:47 AM, David L. Jones wrote:
>>
>>>>> Just thought some might be interested in hearing our recent guest on
>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>> Magic" fame:
>>>>> http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>
>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>> other talk over almost 1 1/12 hours.
>>
>>>>> Dave.
>>
>>>> HJ has a mixture of good stuff and complete nonsense.
>>
>>>> I hope you grilled him a bit about his less sensible stuff, like that
>>>> hilariously erroneous video where he attempts to use electrostatics to
>>>> demonstrate that ground currents want to flow under traces.  Of course,
>>>> the impedance levels are millions of times too high for inductance to be
>>>> a factor in that demo, but never mind.    Have a look athttp://www.sigcon.com/Pubs/news/8_08.htmforthe whole ridiculous thing.
>>
>>>> (The current path is determined by corona discharge at the sharp corners
>>>> of the metal squares--if you look at all closely, you'll see that the
>>>> discharges always want to go out the corners of the squares.)
>>
>>>> Cheers
>>
>>>> Phil Hobbs
>>
>>> That is pretty silly.
>>> But certainly it's a good idea to keep a nice unbroken ground plane
>>> under the signal(s) that you really care about.
>>
>>> George H.
>>
>> I don't disagree with you there.  But I have small respect for someone
>> who makes his living peddling that sort of cargo-cult stuff.  If he ever
>> corrected himself, or offered actual real-world data or simulations, I'd
>> pay attention.  As it is, his stuff is like an old time medicine
>> show--the willow bark tea works, the snake oil doesn't, no apparent
>> effort is expended to sort them out.
>>
>> Remember the little boy in the story:  "Why do you keep snapping your
>> fingers, Bobby?" "To keep polar bears away."  "But there isn't a polar
>> bear within 2000 miles of here!"  "Works great, doesn't it?"
>
> Grin,  I've never read any of Ho Jo's books.  I figured I don't know
> enough to separate the chaff from the grain.
>>
>> Read Morrison instead.
>
> ? Ralph Morrison on Grounding and sheilding?  (the only Morrison on my
> shelf) Or someone else?
>
> George H.


Right.  Later editions have more on signal integrity.  I've been meaning 
to get a copy of the fifth edition.

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

On Wed, 11 Jan 2012 02:16:54 -0800 (PST), Bill Sloman
<bill.sloman@gmail.com> wrote:

>On Jan 11, 4:04�am, "David L. Jones" <altz...@gmail.com> wrote:
>> On Jan 11, 4:08�am,BillSloman<bill.slo...@gmail.com> wrote:
>>
>> > On Jan 11, 1:06 am, "David L. Jones" <altz...@gmail.com> wrote:
>>
>> > > On Jan 11, 5:09 am, John Larkin
>>
>> > > <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
>> > > > Did you have to pay him? How much?
>>
>> > > No, he was not paid, non of our guests are.
>> > > We invite them on and they graciously agree to give up their time to
>> > > participate.
>>
>> > Rather like authors going on "signing tours" to get a bit more
>> > publicity for the books they have written.
>>
>> No, not at all.
>> We liked him so invited him on the show, he did not approach us.
>> He was kind enough to come on and be a guest without any agenda at
>> all.
>
>Lucky him. There can't be all that many hosts who don't know how
>marginal his stuff actually is. Rather like Michelin's lowest grade of
>approval - useful in the area, at the price. His books aren't cheap,
>but they are cheaper than a google search or a couple of hours in a
>good technical library.

He makes a lot of money consulting, privately and at conferences. He
once challenged anyone to debate him on some controversial point, the
gotcha being that you'd have to pay him $600 to get past the door and
debate.

John

On Jan 11, 8:10 pm, Jim Thompson <To-Email-Use-The-Envelope-I...@On-My-
Web-Site.com> wrote:
> On Wed, 11 Jan 2012 10:43:15 -0800, John Larkin
>
>
>
>
>
>
>
>
>
> <jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> >On Tue, 10 Jan 2012 18:02:50 -0800 (PST),BillSloman
> ><bill.slo...@gmail.com> wrote:
>
> >>On Jan 10, 4:55 pm, John Devereux <j...@devereux.me.uk> wrote:
> >>> Robert Macy <robert.a.m...@gmail.com> writes:
> >>> > On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org> wrote:
> >>> >> On Jan 10, 7:47 am, "David L. Jones" <altz...@gmail.com> wrote:
>
> >>> >> > Just thought some might be interested in hearing our recent guest on
> >>> >> > our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> >>> >> > Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>
> >>> >> > Lots of history of the book, signal integrity, Gigabit Ethernet
> >>> >> > development, 90 degree PCB bends, audiophoolery, and a whole bunch of
> >>> >> > other talk over almost 1 1/12 hours.
>
> >>> >> "Black Magic" is more notorious than famous. I own both it and it's
> >>> >> follow-up, and both have got some useful content but they are badly
> >>> >> organised and what useful content they do contain is hard to find.
>
> >>> >> The field is still waiting for a decent textbook on high speed circuit
> >>> >> design and layout.
>
> >>> >> This is one of the few matters on which John Larkin and I seem to
> >>> >> agree.
>
> >>> >> --
> >>> >>BillSloman, Nijmegen
>
> >>> > Perhaps, it is time for the first ever 'conference' book written by a
> >>> > consortium of engineers/scientists.
>
> >>> > Put my name in for proffreading.  :)
>
> >>> Great idea. Perhaps John Larkin, Jim Thompson andBillSlomancould
> >>> collaborate on it.
>
> >>> Sure that will work out well... :)
>
> >>I'm not sure what Jim Thompson might contribute. I've seen papers that
> >>worry about the characteristic impedance of connections on the silicon
> >>(or whatever) inside integrated circuits,
>
> Written by clueless PhD's trying the publish or perish route :-)

The authors affiliations seemed to be with the semiconductor firms,
but that doesn't stop them from being clueless Ph.D.s.

> >>but I don't have the feeling
> >>that Jim designs stuff that's big enough and fast enough for him to
> >>need to know much about it.
>
> What a fundamental fathead you are, Slowman.  Even Larkin knows I've
> designed quite a bit of PECL.

We all know that - you tell us about it at every possible opportunity.
None of its big enough that you are going to have start treating
interconnection on the chip as transmission lines.

> I have chips out there, commercial successes, running at 5GHz.

So what. 5GHz is 200psec and light travels about 6cm in that period -
I'd be surprised if any of your chips were as big as 1cm across. You
really don't have to worry about reflections from discontinuities in
the connections across you chips..

> >I get the impression that most interconnects inside ICs are primarily
> >distributed R-C things, not real transmission lines at all.
> >Propagation speed of interconnects is a big deal in routing fast logic
> >chips, but the speed of light isn't the issue.

Me too.

--
Bill Sloman, Nijmegen

On Wed, 11 Jan 2012 14:22:11 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 01/11/2012 01:43 PM, John Larkin wrote:
>> On Tue, 10 Jan 2012 18:02:50 -0800 (PST), Bill Sloman
>> <bill.sloman@gmail.com>  wrote:
>>
>>> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk>  wrote:
>>>> Robert Macy<robert.a.m...@gmail.com>  writes:
>>>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org>  wrote:
>>>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com>  wrote:
>>>>
>>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>>>
>>>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>>>> other talk over almost 1 1/12 hours.
>>>>
>>>>>> "Black Magic" is more notorious than famous. I own both it and it's
>>>>>> follow-up, and both have got some useful content but they are badly
>>>>>> organised and what useful content they do contain is hard to find.
>>>>
>>>>>> The field is still waiting for a decent textbook on high speed circuit
>>>>>> design and layout.
>>>>
>>>>>> This is one of the few matters on which John Larkin and I seem to
>>>>>> agree.
>>>>
>>>>>> --
>>>>>> BillSloman, Nijmegen
>>>>
>>>>> Perhaps, it is time for the first ever 'conference' book written by a
>>>>> consortium of engineers/scientists.
>>>>
>>>>> Put my name in for proffreading.  :)
>>>>
>>>> Great idea. Perhaps John Larkin, Jim Thompson and Bill Sloman could
>>>> collaborate on it.
>>>>
>>>> Sure that will work out well... :)
>>>
>>> I'm not sure what Jim Thompson might contribute. I've seen papers that
>>> worry about the characteristic impedance of connections on the silicon
>>> (or whatever) inside integrated circuits, but I don't have the feeling
>>> that Jim designs stuff that's big enough and fast enough for him to
>>> need to know much about it.
>>
>> I get the impression that most interconnects inside ICs are primarily
>> distributed R-C things, not real transmission lines at all.
>> Propagation speed of interconnects is a big deal in routing fast logic
>> chips, but the speed of light isn't the issue.
>>
>>>
>>> Motorola's ECL applications notes on board layout were rather useful,
>>
>> Just don't trust their microstrip equation!
>>
>> John
>>
>
>Yup, all RC transmission lines with repeaters, speed roughly c/10.

The routing delay scales roughly with the square of the length (not at all
linear).  Yes, it's often faster to buffer the middle of a long line.  In the
PPC970/G5, there were several nets with three and four repeaters.  Even
numbers work better, though.  ;-)

On 01/11/2012 08:00 PM, Bill Sloman wrote:
> On Jan 11, 8:10 pm, Jim Thompson<To-Email-Use-The-Envelope-I...@On-My-
> Web-Site.com>  wrote:
>> On Wed, 11 Jan 2012 10:43:15 -0800, John Larkin
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> <jjlar...@highNOTlandTHIStechnologyPART.com>  wrote:
>>> On Tue, 10 Jan 2012 18:02:50 -0800 (PST),BillSloman
>>> <bill.slo...@gmail.com>  wrote:
>>
>>>> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk>  wrote:
>>>>> Robert Macy<robert.a.m...@gmail.com>  writes:
>>>>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org>  wrote:
>>>>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com>  wrote:
>>
>>>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>
>>>>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>>>>> other talk over almost 1 1/12 hours.
>>
>>>>>>> "Black Magic" is more notorious than famous. I own both it and it's
>>>>>>> follow-up, and both have got some useful content but they are badly
>>>>>>> organised and what useful content they do contain is hard to find.
>>
>>>>>>> The field is still waiting for a decent textbook on high speed circuit
>>>>>>> design and layout.
>>
>>>>>>> This is one of the few matters on which John Larkin and I seem to
>>>>>>> agree.
>>
>>>>>>> --
>>>>>>> BillSloman, Nijmegen
>>
>>>>>> Perhaps, it is time for the first ever 'conference' book written by a
>>>>>> consortium of engineers/scientists.
>>
>>>>>> Put my name in for proffreading.  :)
>>
>>>>> Great idea. Perhaps John Larkin, Jim Thompson andBillSlomancould
>>>>> collaborate on it.
>>
>>>>> Sure that will work out well... :)
>>
>>>> I'm not sure what Jim Thompson might contribute. I've seen papers that
>>>> worry about the characteristic impedance of connections on the silicon
>>>> (or whatever) inside integrated circuits,
>>
>> Written by clueless PhD's trying the publish or perish route :-)
>
> The authors affiliations seemed to be with the semiconductor firms,
> but that doesn't stop them from being clueless Ph.D.s.
>
>>>> but I don't have the feeling
>>>> that Jim designs stuff that's big enough and fast enough for him to
>>>> need to know much about it.
>>
>> What a fundamental fathead you are, Slowman.  Even Larkin knows I've
>> designed quite a bit of PECL.
>
> We all know that - you tell us about it at every possible opportunity.
> None of its big enough that you are going to have start treating
> interconnection on the chip as transmission lines.

Even large processors are all RC internally.  (Part of my previous job 
was helping set IBM's optical interconnection strategy, so we went over 
all that wire stuff in gory detail.)  There was a DARPA program a few 
years back that tried pushing copper interconnects to much lower 
speed/power points, but inductance never became a big factor.

Cheers

Phil Hobbs


-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

On 01/11/2012 07:49 PM, Bill Sloman wrote:
> On Jan 11, 8:22 pm, Phil Hobbs
> <pcdhSpamMeSensel...@electrooptical.net>  wrote:
>> On 01/11/2012 01:43 PM, John Larkin wrote:
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>> On Tue, 10 Jan 2012 18:02:50 -0800 (PST),BillSloman
>>> <bill.slo...@gmail.com>    wrote:
>>
>>>> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk>    wrote:
>>>>> Robert Macy<robert.a.m...@gmail.com>    writes:
>>>>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org>    wrote:
>>>>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com>    wrote:
>>
>>>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>
>>>>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>>>>> other talk over almost 1 1/12 hours.
>>
>>>>>>> "Black Magic" is more notorious than famous. I own both it and it's
>>>>>>> follow-up, and both have got some useful content but they are badly
>>>>>>> organised and what useful content they do contain is hard to find.
>>
>>>>>>> The field is still waiting for a decent textbook on high speed circuit
>>>>>>> design and layout.
>>
>>>>>>> This is one of the few matters on which John Larkin and I seem to
>>>>>>> agree.
>>
>>>>>> Perhaps, it is time for the first ever 'conference' book written by a
>>>>>> consortium of engineers/scientists.
>>
>>>>>> Put my name in for proffreading.  :)
>>
>>>>> Great idea. Perhaps John Larkin, Jim Thompson and Bill Sloman could
>>>>> collaborate on it.
>>
>>>>> Sure that will work out well... :)
>>
>>>> I'm not sure what Jim Thompson might contribute. I've seen papers that
>>>> worry about the characteristic impedance of connections on the silicon
>>>> (or whatever) inside integrated circuits, but I don't have the feeling
>>>> that Jim designs stuff that's big enough and fast enough for him to
>>>> need to know much about it.
>>
>>> I get the impression that most interconnects inside ICs are primarily
>>> distributed R-C things, not real transmission lines at all.
>>> Propagation speed of interconnects is a big deal in routing fast logic
>>> chips, but the speed of light isn't the issue.
>>
>>>> Motorola's ECL applications notes on board layout were rather useful,
>>
>>> Just don't trust their microstrip equation!
>
> They looked okay in the range 50R to 75R. Specialised textbooks give
> longer and more complicated expressions that give rather different
> results for microstrips and strip-line with higher and lower
> characteristic impedances.
>
>> Yup, all RC transmission lines with repeaters, speed roughly c/10.
>
> I wonder what Dr. Hobbs thinks he is talking about - the Motorola  ECL
> application notes discussed proper microstrip and stripline
> transmission lines, where the propagation delay is basically that of
> electromagenetic waves in dielectric - something around two-thirds of
> the speed of light in vacuum (depending on the dielectric constant of
> the substrate).
>

On-chip interconnects, even the fatwire levels, are all RC.  Once you 
get off the chip, you have to worry about transmission line effects, but 
the losses in chip wiring are so horrendous that you have to use 
multiple repeaters to go a couple of centimters. The delays in the 
repeaters, and the edge degradation due to RC rolloff, produce a net 
propagation speed of about c/10.  Of course my information is two or 
three years old at this point, but I wouldn't expect inductance to get 
more important anytime soon.

Cheers

Phil Hobbs


-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

On 01/11/2012 08:26 PM, krw@att.bizzzzzzzzzzzz wrote:
> On Wed, 11 Jan 2012 14:22:11 -0500, Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net>  wrote:
>
>> On 01/11/2012 01:43 PM, John Larkin wrote:
>>> On Tue, 10 Jan 2012 18:02:50 -0800 (PST), Bill Sloman
>>> <bill.sloman@gmail.com>   wrote:
>>>
>>>> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk>   wrote:
>>>>> Robert Macy<robert.a.m...@gmail.com>   writes:
>>>>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org>   wrote:
>>>>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com>   wrote:
>>>>>
>>>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>>>>
>>>>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>>>>> other talk over almost 1 1/12 hours.
>>>>>
>>>>>>> "Black Magic" is more notorious than famous. I own both it and it's
>>>>>>> follow-up, and both have got some useful content but they are badly
>>>>>>> organised and what useful content they do contain is hard to find.
>>>>>
>>>>>>> The field is still waiting for a decent textbook on high speed circuit
>>>>>>> design and layout.
>>>>>
>>>>>>> This is one of the few matters on which John Larkin and I seem to
>>>>>>> agree.
>>>>>
>>>>>>> --
>>>>>>> BillSloman, Nijmegen
>>>>>
>>>>>> Perhaps, it is time for the first ever 'conference' book written by a
>>>>>> consortium of engineers/scientists.
>>>>>
>>>>>> Put my name in for proffreading.  :)
>>>>>
>>>>> Great idea. Perhaps John Larkin, Jim Thompson and Bill Sloman could
>>>>> collaborate on it.
>>>>>
>>>>> Sure that will work out well... :)
>>>>
>>>> I'm not sure what Jim Thompson might contribute. I've seen papers that
>>>> worry about the characteristic impedance of connections on the silicon
>>>> (or whatever) inside integrated circuits, but I don't have the feeling
>>>> that Jim designs stuff that's big enough and fast enough for him to
>>>> need to know much about it.
>>>
>>> I get the impression that most interconnects inside ICs are primarily
>>> distributed R-C things, not real transmission lines at all.
>>> Propagation speed of interconnects is a big deal in routing fast logic
>>> chips, but the speed of light isn't the issue.
>>>
>>>>
>>>> Motorola's ECL applications notes on board layout were rather useful,
>>>
>>> Just don't trust their microstrip equation!
>>>
>>> John
>>>
>>
>> Yup, all RC transmission lines with repeaters, speed roughly c/10.
>
> The routing delay scales roughly with the square of the length (not at all
> linear).  Yes, it's often faster to buffer the middle of a long line.  In the
> PPC970/G5, there were several nets with three and four repeaters.  Even
> numbers work better, though.  ;-)

In the limit of long lines, that's true.  However, you can't build chips 
in that limit, because the bandwidth goes down quadratically with length 
as well.  To maintain speed, you have to use repeaters, and maintaining 
2-3 GHz clock rates with reasonable jitter requires spacing them at 
something like 1 mm intervals on long lines.  In an optimized layout, 
that turns out to produce a roughly constant propagation speed of c/10 
or so.

Cheers

Phil "Former on-chip optical interconnect person" Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

On Wed, 11 Jan 2012 16:49:18 -0800 (PST), Bill Sloman
<bill.sloman@ieee.org> wrote:

>On Jan 11, 8:22�pm, Phil Hobbs
><pcdhSpamMeSensel...@electrooptical.net> wrote:
>> On 01/11/2012 01:43 PM, John Larkin wrote:
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> > On Tue, 10 Jan 2012 18:02:50 -0800 (PST),BillSloman
>> > <bill.slo...@gmail.com> �wrote:
>>
>> >> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk> �wrote:
>> >>> Robert Macy<robert.a.m...@gmail.com> �writes:
>> >>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org> �wrote:
>> >>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com> �wrote:
>>
>> >>>>>> Just thought some might be interested in hearing our recent guest on
>> >>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>> >>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>
>> >>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>> >>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>> >>>>>> other talk over almost 1 1/12 hours.
>>
>> >>>>> "Black Magic" is more notorious than famous. I own both it and it's
>> >>>>> follow-up, and both have got some useful content but they are badly
>> >>>>> organised and what useful content they do contain is hard to find.
>>
>> >>>>> The field is still waiting for a decent textbook on high speed circuit
>> >>>>> design and layout.
>>
>> >>>>> This is one of the few matters on which John Larkin and I seem to
>> >>>>> agree.
>>
>> >>>> Perhaps, it is time for the first ever 'conference' book written by a
>> >>>> consortium of engineers/scientists.
>>
>> >>>> Put my name in for proffreading. �:)
>>
>> >>> Great idea. Perhaps John Larkin, Jim Thompson and Bill Sloman could
>> >>> collaborate on it.
>>
>> >>> Sure that will work out well... :)
>>
>> >> I'm not sure what Jim Thompson might contribute. I've seen papers that
>> >> worry about the characteristic impedance of connections on the silicon
>> >> (or whatever) inside integrated circuits, but I don't have the feeling
>> >> that Jim designs stuff that's big enough and fast enough for him to
>> >> need to know much about it.
>>
>> > I get the impression that most interconnects inside ICs are primarily
>> > distributed R-C things, not real transmission lines at all.
>> > Propagation speed of interconnects is a big deal in routing fast logic
>> > chips, but the speed of light isn't the issue.
>>
>> >> Motorola's ECL applications notes on board layout were rather useful,
>>
>> > Just don't trust their microstrip equation!
>
>They looked okay in the range 50R to 75R.


Yup. And they give silly, even negative, impedances for traces outside
a narrow width zone.


 Specialised textbooks give
>longer and more complicated expressions that give rather different
>results for microstrips and strip-line with higher and lower
>characteristic impedances.
>
>> Yup, all RC transmission lines with repeaters, speed roughly c/10.
>
>I wonder what Dr. Hobbs thinks he is talking about

The fact that on-chip interconnects are usually dominated by
resistance and capacitance, and don't behave like the transmission
lines you're used to. Since the risetime of a distributed R-C line
degrades as length-squared or something horrible like that, it makes
sense to insert active buffers in long runs.

I believe he has a bunch of direct experience in this area. 

 - the Motorola  ECL
>application notes discussed proper microstrip and stripline
>transmission lines, where the propagation delay is basically that of
>electromagenetic waves in dielectric - something around two-thirds of
>the speed of light in vacuum (depending on the dielectric constant of
>the substrate).

They also cautioned against sharp corners, a silly warning at ECL
speeds.

John

On Wed, 11 Jan 2012 20:26:50 -0500, "krw@att.bizzzzzzzzzzzz"
<krw@att.bizzzzzzzzzzzz> wrote:

>On Wed, 11 Jan 2012 14:22:11 -0500, Phil Hobbs
><pcdhSpamMeSenseless@electrooptical.net> wrote:
>
>>On 01/11/2012 01:43 PM, John Larkin wrote:
>>> On Tue, 10 Jan 2012 18:02:50 -0800 (PST), Bill Sloman
>>> <bill.sloman@gmail.com>  wrote:
>>>
>>>> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk>  wrote:
>>>>> Robert Macy<robert.a.m...@gmail.com>  writes:
>>>>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org>  wrote:
>>>>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com>  wrote:
>>>>>
>>>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>>>>
>>>>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>>>>> other talk over almost 1 1/12 hours.
>>>>>
>>>>>>> "Black Magic" is more notorious than famous. I own both it and it's
>>>>>>> follow-up, and both have got some useful content but they are badly
>>>>>>> organised and what useful content they do contain is hard to find.
>>>>>
>>>>>>> The field is still waiting for a decent textbook on high speed circuit
>>>>>>> design and layout.
>>>>>
>>>>>>> This is one of the few matters on which John Larkin and I seem to
>>>>>>> agree.
>>>>>
>>>>>>> --
>>>>>>> BillSloman, Nijmegen
>>>>>
>>>>>> Perhaps, it is time for the first ever 'conference' book written by a
>>>>>> consortium of engineers/scientists.
>>>>>
>>>>>> Put my name in for proffreading.  :)
>>>>>
>>>>> Great idea. Perhaps John Larkin, Jim Thompson and Bill Sloman could
>>>>> collaborate on it.
>>>>>
>>>>> Sure that will work out well... :)
>>>>
>>>> I'm not sure what Jim Thompson might contribute. I've seen papers that
>>>> worry about the characteristic impedance of connections on the silicon
>>>> (or whatever) inside integrated circuits, but I don't have the feeling
>>>> that Jim designs stuff that's big enough and fast enough for him to
>>>> need to know much about it.
>>>
>>> I get the impression that most interconnects inside ICs are primarily
>>> distributed R-C things, not real transmission lines at all.
>>> Propagation speed of interconnects is a big deal in routing fast logic
>>> chips, but the speed of light isn't the issue.
>>>
>>>>
>>>> Motorola's ECL applications notes on board layout were rather useful,
>>>
>>> Just don't trust their microstrip equation!
>>>
>>> John
>>>
>>
>>Yup, all RC transmission lines with repeaters, speed roughly c/10.
>
>The routing delay scales roughly with the square of the length (not at all
>linear).  Yes, it's often faster to buffer the middle of a long line.  In the
>PPC970/G5, there were several nets with three and four repeaters.  Even
>numbers work better, though.  ;-)


Getcher inverter for free!

John

On Wed, 11 Jan 2012 21:02:07 -0500, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 01/11/2012 08:26 PM, krw@att.bizzzzzzzzzzzz wrote:
>> On Wed, 11 Jan 2012 14:22:11 -0500, Phil Hobbs
>> <pcdhSpamMeSenseless@electrooptical.net>  wrote:
>>
>>> On 01/11/2012 01:43 PM, John Larkin wrote:
>>>> On Tue, 10 Jan 2012 18:02:50 -0800 (PST), Bill Sloman
>>>> <bill.sloman@gmail.com>   wrote:
>>>>
>>>>> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk>   wrote:
>>>>>> Robert Macy<robert.a.m...@gmail.com>   writes:
>>>>>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org>   wrote:
>>>>>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com>   wrote:
>>>>>>
>>>>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>>>>>
>>>>>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>>>>>> other talk over almost 1 1/12 hours.
>>>>>>
>>>>>>>> "Black Magic" is more notorious than famous. I own both it and it's
>>>>>>>> follow-up, and both have got some useful content but they are badly
>>>>>>>> organised and what useful content they do contain is hard to find.
>>>>>>
>>>>>>>> The field is still waiting for a decent textbook on high speed circuit
>>>>>>>> design and layout.
>>>>>>
>>>>>>>> This is one of the few matters on which John Larkin and I seem to
>>>>>>>> agree.
>>>>>>
>>>>>>>> --
>>>>>>>> BillSloman, Nijmegen
>>>>>>
>>>>>>> Perhaps, it is time for the first ever 'conference' book written by a
>>>>>>> consortium of engineers/scientists.
>>>>>>
>>>>>>> Put my name in for proffreading.  :)
>>>>>>
>>>>>> Great idea. Perhaps John Larkin, Jim Thompson and Bill Sloman could
>>>>>> collaborate on it.
>>>>>>
>>>>>> Sure that will work out well... :)
>>>>>
>>>>> I'm not sure what Jim Thompson might contribute. I've seen papers that
>>>>> worry about the characteristic impedance of connections on the silicon
>>>>> (or whatever) inside integrated circuits, but I don't have the feeling
>>>>> that Jim designs stuff that's big enough and fast enough for him to
>>>>> need to know much about it.
>>>>
>>>> I get the impression that most interconnects inside ICs are primarily
>>>> distributed R-C things, not real transmission lines at all.
>>>> Propagation speed of interconnects is a big deal in routing fast logic
>>>> chips, but the speed of light isn't the issue.
>>>>
>>>>>
>>>>> Motorola's ECL applications notes on board layout were rather useful,
>>>>
>>>> Just don't trust their microstrip equation!
>>>>
>>>> John
>>>>
>>>
>>> Yup, all RC transmission lines with repeaters, speed roughly c/10.
>>
>> The routing delay scales roughly with the square of the length (not at all
>> linear).  Yes, it's often faster to buffer the middle of a long line.  In the
>> PPC970/G5, there were several nets with three and four repeaters.  Even
>> numbers work better, though.  ;-)
>
>In the limit of long lines, that's true.  However, you can't build chips 
>in that limit, because the bandwidth goes down quadratically with length 
>as well.  To maintain speed, you have to use repeaters, and maintaining 
>2-3 GHz clock rates with reasonable jitter requires spacing them at 
>something like 1 mm intervals on long lines.  In an optimized layout, 
>that turns out to produce a roughly constant propagation speed of c/10 
>or so.
>
>Cheers
>
>Phil "Former on-chip optical interconnect person" Hobbs

Our on-chip delay models were pretty much l^2 (RC, where c ~ l*w and R~l).  A
constant delay would imply an LC line, no?

On 01/11/2012 10:10 PM, krw@att.bizzzzzzzzzzzz wrote:
> On Wed, 11 Jan 2012 21:02:07 -0500, Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net>  wrote:
>
>> On 01/11/2012 08:26 PM, krw@att.bizzzzzzzzzzzz wrote:
>>> On Wed, 11 Jan 2012 14:22:11 -0500, Phil Hobbs
>>> <pcdhSpamMeSenseless@electrooptical.net>   wrote:
>>>
>>>> On 01/11/2012 01:43 PM, John Larkin wrote:
>>>>> On Tue, 10 Jan 2012 18:02:50 -0800 (PST), Bill Sloman
>>>>> <bill.sloman@gmail.com>    wrote:
>>>>>
>>>>>> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk>    wrote:
>>>>>>> Robert Macy<robert.a.m...@gmail.com>    writes:
>>>>>>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org>    wrote:
>>>>>>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com>    wrote:
>>>>>>>
>>>>>>>>>> Just thought some might be interested in hearing our recent guest on
>>>>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
>>>>>>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>>>>>>>
>>>>>>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
>>>>>>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
>>>>>>>>>> other talk over almost 1 1/12 hours.
>>>>>>>
>>>>>>>>> "Black Magic" is more notorious than famous. I own both it and it's
>>>>>>>>> follow-up, and both have got some useful content but they are badly
>>>>>>>>> organised and what useful content they do contain is hard to find.
>>>>>>>
>>>>>>>>> The field is still waiting for a decent textbook on high speed circuit
>>>>>>>>> design and layout.
>>>>>>>
>>>>>>>>> This is one of the few matters on which John Larkin and I seem to
>>>>>>>>> agree.
>>>>>>>
>>>>>>>>> --
>>>>>>>>> BillSloman, Nijmegen
>>>>>>>
>>>>>>>> Perhaps, it is time for the first ever 'conference' book written by a
>>>>>>>> consortium of engineers/scientists.
>>>>>>>
>>>>>>>> Put my name in for proffreading.  :)
>>>>>>>
>>>>>>> Great idea. Perhaps John Larkin, Jim Thompson and Bill Sloman could
>>>>>>> collaborate on it.
>>>>>>>
>>>>>>> Sure that will work out well... :)
>>>>>>
>>>>>> I'm not sure what Jim Thompson might contribute. I've seen papers that
>>>>>> worry about the characteristic impedance of connections on the silicon
>>>>>> (or whatever) inside integrated circuits, but I don't have the feeling
>>>>>> that Jim designs stuff that's big enough and fast enough for him to
>>>>>> need to know much about it.
>>>>>
>>>>> I get the impression that most interconnects inside ICs are primarily
>>>>> distributed R-C things, not real transmission lines at all.
>>>>> Propagation speed of interconnects is a big deal in routing fast logic
>>>>> chips, but the speed of light isn't the issue.
>>>>>
>>>>>>
>>>>>> Motorola's ECL applications notes on board layout were rather useful,
>>>>>
>>>>> Just don't trust their microstrip equation!
>>>>>
>>>>> John
>>>>>
>>>>
>>>> Yup, all RC transmission lines with repeaters, speed roughly c/10.
>>>
>>> The routing delay scales roughly with the square of the length (not at all
>>> linear).  Yes, it's often faster to buffer the middle of a long line.  In the
>>> PPC970/G5, there were several nets with three and four repeaters.  Even
>>> numbers work better, though.  ;-)
>>
>> In the limit of long lines, that's true.  However, you can't build chips
>> in that limit, because the bandwidth goes down quadratically with length
>> as well.  To maintain speed, you have to use repeaters, and maintaining
>> 2-3 GHz clock rates with reasonable jitter requires spacing them at
>> something like 1 mm intervals on long lines.  In an optimized layout,
>> that turns out to produce a roughly constant propagation speed of c/10
>> or so.
>>
>> Cheers
>>
>> Phil "Former on-chip optical interconnect person" Hobbs
>
> Our on-chip delay models were pretty much l^2 (RC, where c ~ l*w and R~l).  A
> constant delay would imply an LC line, no?
>

No, it just implies a constant distance between repeaters.  The optimal 
spacing doesn't depend on how many hops you have, so N hops gives N 
times the delay of one hop.

Cheers

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510
845-480-2058

hobbs at electrooptical dot net
http://electrooptical.net

On Jan 12, 3:13 am, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Wed, 11 Jan 2012 16:49:18 -0800 (PST),BillSloman
>
> <bill.slo...@ieee.org> wrote:
> >On Jan 11, 8:22 pm, Phil Hobbs
> ><pcdhSpamMeSensel...@electrooptical.net> wrote:
> >> On 01/11/2012 01:43 PM, John Larkin wrote:
>
> >> > On Tue, 10 Jan 2012 18:02:50 -0800 (PST),BillSloman
> >> > <bill.slo...@gmail.com> wrote:
>
> >> >> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk> wrote:
> >> >>> Robert Macy<robert.a.m...@gmail.com> writes:
> >> >>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org> wrote:
> >> >>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com> wrote:
>
> >> >>>>>> Just thought some might be interested in hearing our recent guest on
> >> >>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> >> >>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>
> >> >>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
> >> >>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
> >> >>>>>> other talk over almost 1 1/12 hours.
>
> >> >>>>> "Black Magic" is more notorious than famous. I own both it and it's
> >> >>>>> follow-up, and both have got some useful content but they are badly
> >> >>>>> organised and what useful content they do contain is hard to find.
>
> >> >>>>> The field is still waiting for a decent textbook on high speed circuit
> >> >>>>> design and layout.
>
> >> >>>>> This is one of the few matters on which John Larkin and I seem to
> >> >>>>> agree.
>
> >> >>>> Perhaps, it is time for the first ever 'conference' book written by a
> >> >>>> consortium of engineers/scientists.
>
> >> >>>> Put my name in for proffreading. :)
>
> >> >>> Great idea. Perhaps John Larkin, Jim Thompson andBillSlomancould
> >> >>> collaborate on it.
>
> >> >>> Sure that will work out well... :)
>
> >> >> I'm not sure what Jim Thompson might contribute. I've seen papers that
> >> >> worry about the characteristic impedance of connections on the silicon
> >> >> (or whatever) inside integrated circuits, but I don't have the feeling
> >> >> that Jim designs stuff that's big enough and fast enough for him to
> >> >> need to know much about it.
>
> >> > I get the impression that most interconnects inside ICs are primarily
> >> > distributed R-C things, not real transmission lines at all.
> >> > Propagation speed of interconnects is a big deal in routing fast logic
> >> > chips, but the speed of light isn't the issue.
>
> >> >> Motorola's ECL applications notes on board layout were rather useful,
>
> >> > Just don't trust their microstrip equation!
>
> >They looked okay in the range 50R to 75R.
>
> Yup. And they give silly, even negative, impedances for traces outside
> a narrow width zone.

Which is more or less what I went on to say in the next paragraph -
you seem to suffer from premature ejeculation.

> >Specialised textbooks give
> >longer and more complicated expressions that give rather different
> >results for microstrips and strip-line with higher and lower
> >characteristic impedances.
>
> >> Yup, all RC transmission lines with repeaters, speed roughly c/10.
>
> >I wonder what Dr. Hobbs thinks he is talking about
>
> The fact that on-chip interconnects are usually dominated by
> resistance and capacitance, and don't behave like the transmission
> lines you're used to. Since the risetime of a distributed R-C line
> degrades as length-squared or something horrible like that, it makes
> sense to insert active buffers in long runs.

Which didn't have much to do with the point that the Motorola ECL data
books used formulas for trace impedance that only worked well over a
narrow - if useful - range of trace impedances. It's entirely relevant
to the point that Jim Thompson doesn't have to know much about laying
out printed circuit boards for signals with short transition times,
but Phil didn't bother to make it clear that he was addressing that
particular question.

> I believe he has a bunch of direct experience in this area.

> > - the Motorola  ECL
> >application notes discussed proper microstrip and stripline
> >transmission lines, where the propagation delay is basically that of
> >electromagenetic waves in dielectric - something around two-thirds of
> >the speed of light in vacuum (depending on the dielectric constant of
> >the substrate).
>
> They also cautioned against sharp corners, a silly warning at ECL
> speeds.

At current ECLinPS speeds everything gets averaged over a few
millimetres of track. The extra capacitance implicit in a right-angle
bend on a 5OR track might be perceptible, but you can pretty much
eliminate it by chamfering the corner, or making two 45-degree bends
in quick succession.

--
Bill Sloman, Nijmegen

On Jan 12, 2:56 am, Phil Hobbs
<pcdhSpamMeSensel...@electrooptical.net> wrote:
> On 01/11/2012 07:49 PM,BillSlomanwrote:
>
>
>
>
>
>
>
>
>
> > On Jan 11, 8:22 pm, Phil Hobbs
> > <pcdhSpamMeSensel...@electrooptical.net>  wrote:
> >> On 01/11/2012 01:43 PM, John Larkin wrote:
>
> >>> On Tue, 10 Jan 2012 18:02:50 -0800 (PST),BillSloman
> >>> <bill.slo...@gmail.com>    wrote:
>
> >>>> On Jan 10, 4:55 pm, John Devereux<j...@devereux.me.uk>    wrote:
> >>>>> Robert Macy<robert.a.m...@gmail.com>    writes:
> >>>>>> On Jan 10, 2:28 am,BillSloman<bill.slo...@ieee.org>    wrote:
> >>>>>>> On Jan 10, 7:47 am, "David L. Jones"<altz...@gmail.com>    wrote:
>
> >>>>>>>> Just thought some might be interested in hearing our recent guest on
> >>>>>>>> our Amp Hour radio show, Dr Howard Johnson of "Handbook of Black
> >>>>>>>> Magic" fame:http://www.theamphour.com/2012/01/10/the-amp-hour-77-winsome-waveform...
>
> >>>>>>>> Lots of history of the book, signal integrity, Gigabit Ethernet
> >>>>>>>> development, 90 degree PCB bends, audiophoolery, and a whole bunch of
> >>>>>>>> other talk over almost 1 1/12 hours.
>
> >>>>>>> "Black Magic" is more notorious than famous. I own both it and it's
> >>>>>>> follow-up, and both have got some useful content but they are badly
> >>>>>>> organised and what useful content they do contain is hard to find.
>
> >>>>>>> The field is still waiting for a decent textbook on high speed circuit
> >>>>>>> design and layout.
>
> >>>>>>> This is one of the few matters on which John Larkin and I seem to
> >>>>>>> agree.
>
> >>>>>> Perhaps, it is time for the first ever 'conference' book written by a
> >>>>>> consortium of engineers/scientists.
>
> >>>>>> Put my name in for proffreading.  :)
>
> >>>>> Great idea. Perhaps John Larkin, Jim Thompson andBillSlomancould
> >>>>> collaborate on it.
>
> >>>>> Sure that will work out well... :)
>
> >>>> I'm not sure what Jim Thompson might contribute. I've seen papers that
> >>>> worry about the characteristic impedance of connections on the silicon
> >>>> (or whatever) inside integrated circuits, but I don't have the feeling
> >>>> that Jim designs stuff that's big enough and fast enough for him to
> >>>> need to know much about it.
>
> >>> I get the impression that most interconnects inside ICs are primarily
> >>> distributed R-C things, not real transmission lines at all.
> >>> Propagation speed of interconnects is a big deal in routing fast logic
> >>> chips, but the speed of light isn't the issue.
>
> >>>> Motorola's ECL applications notes on board layout were rather useful,
>
> >>> Just don't trust their microstrip equation!
>
> > They looked okay in the range 50R to 75R. Specialised textbooks give
> > longer and more complicated expressions that give rather different
> > results for microstrips and strip-line with higher and lower
> > characteristic impedances.
>
> >> Yup, all RC transmission lines with repeaters, speed roughly c/10.
>
> > I wonder what Dr. Hobbs thinks he is talking about - the Motorola  ECL
> > application notes discussed proper microstrip and stripline
> > transmission lines, where the propagation delay is basically that of
> > electromagenetic waves in dielectric - something around two-thirds of
> > the speed of light in vacuum (depending on the dielectric constant of
> > the substrate).
>
> On-chip interconnects, even the fatwire levels, are all RC.  Once you
> get off the chip, you have to worry about transmission line effects, but
> the losses in chip wiring are so horrendous that you have to use
> multiple repeaters to go a couple of centimters. The delays in the
> repeaters, and the edge degradation due to RC rolloff, produce a net
> propagation speed of about c/10.  Of course my information is two or
> three years old at this point, but I wouldn't expect inductance to get
> more important anytime soon.

It's an entirely valid point, but you inserted the comment a couple of
paragraphs further down the post than you should have - it looked as
if you were commenting on the limitations of the Motorola ECL
application notes (which were perfectly okay, though they should have
included a caution about the range of validity of the trace-impedance
expressions) rather than on the sort of experience Jim Thompson might
have had in laying out transmission lines (very little to none).

--
Bill Sloman, Nijmegen

On Jan 10, 4:59 pm, John S <Soph...@invalid.org> wrote:
> On 1/10/2012 6:49 PM, John Larkin wrote:
>
> > As is the admonition to never cross slits in planes, fr'instance
> > running a trace above a plane that has multiple pour pours.
>
> > John
>
> Did you mean "multiple poor pours."?  :-)

I think "multiple pour pours" is acutally rather self-fulfilling.

On Thu, 12 Jan 2012 08:51:42 -0800 (PST), Bob
<stephensdigital@gmail.com> wrote:

>On Jan 10, 4:59�pm, John S <Soph...@invalid.org> wrote:
>> On 1/10/2012 6:49 PM, John Larkin wrote:
>>
>> > As is the admonition to never cross slits in planes, fr'instance
>> > running a trace above a plane that has multiple pour pours.
>>
>> > John
>>
>> Did you mean "multiple poor pours."? �:-)
>
>I think "multiple pour pours" is acutally rather self-fulfilling.

Our cat makes noises like that.

John

> >
> >A track across a slit is an antenna. Unless there's another plane
> >underneath covering the slit, in which case it probably doesn't
> >matter.
>
> On a multilyer board, there usually is. But I've done test slits on
> microstrips on 2-sided boards, clear across the board, and not much
> happens. I didn't measure radiated EMI, but signal integrity wasn't
> much affected at 30 ps risetimes.
>
> John
>
>
>

right,  just like a coax cable, a disruption of the shield  won't make a
difference to the signal integrity to one signal in the cable

 but can still make a big difference to the shielding effectiveness or
transfer impedance and therefore crosstalk between traces.

If you run TWO traces over the  gap in the plane, the coupling between the
traces will be increased dramatically.

Mark