🚀 go-pugleaf

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.  ;-)