a diode behaving like a cap

[terry michaels]

Message text written by Rob
>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:

The Varactor or varicap diode is designed to be used as you described. 
Increasing the reverse voltage increases the width of the depletion layer,
and reduces the capacitance.

The other thing about germanium diodes is much greater reverse leakage
current.

Terry Michaels