🚀 go-pugleaf

In article <JON_SREE.91Jan21215810@world.std.com> jon_sree@world.std.com (Jon Sreekanth) writes:
>
>A rather curious query : what is the audio frequency impedance of 
>a reverse biased diode ? Off-hand, one would say, it's high, but
>just how high ? 
>
>Specifically, for a small signal diode like 1N4148, between 0 - 70 C,
>with about 2.5 V or more of reverse bias, is the small signal audio
>impedance at least > 1 Meg ? 10 Meg ?

TI's datasheet (1966, revised 1973) for the 1N4148 sez that the
max capacitance is 4 pF and the max leakage current at 100C is 3
microamperes (with 20V of reverse bias).  Leakage current at room
temp is 0.025 microamps.

So a crude model would be a 6.7Megohm resistor in parallel with a
4pF capacitor.  At 20kHz, 4pF has a capacitive reactance of 2 Megohms.
-- 
 -- Mark Johnson	
 	MIPS Computer Systems, 930 E. Arques M/S 2-02, Sunnyvale, CA 94086
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