a diode behaving like a cap

[Bissell, Harry]

Varactor diodes do this all the time, they change capacitance based on the
reverse voltage (like 2-20V)
and may change capacitance over as much as a 15:1 range (2:1 is more common)
Available from a few pF to about 500pF. Used for R.F. tuning, and sometimes
for tuning H.F. oscillators. I found some in Motorola Small Signal Xstrs,
Fets, and Diodes. P.S. All diodes do this to a small degree (but not real
useful)

> -----Original Message-----
> From:	Rob [SMTP:cyborg0 at GlobalEyes.net]
> Sent:	Friday, January 29, 1999 6:49 PM
> To:	synth-diy at mailhost.bpa.nl
> Subject:	a diode behaving like a cap
> 
> Just wondering if its possible to use the depletion layer of a standard
> reverse biased switching diode to act as a cap...
> in other words, you have a diode put in the wrong way.. So, does the
> depletion layer increase as the reverse voltage increases?
> 
> Another thing: is there any special reactions germanium diodes have
> besides having a .3v bias?
> 
> Rob