You might try searching on "Varactor diode" or "RF varactor diode".  An
example of one is shown here:

http://www.vishay.com/docs/85554/85554.pdf

I don't know if it would be terribly well calibrated, but it might be good
for a quick check. Typical capacitance (and delta capacitance) is on the
order of a few pF for this application.

David Nemeth


-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of Andrew O'Grady
Sent: Friday, May 18, 2007 11:32 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Off-the-shelf product with known C-V

Hello Everyone,

I am using the Keithley 590CV for capacitance-voltage measurements on my
MEMS sensor which actuates when a voltage is applied. I have been getting
some odd results, and the Keithley 590CV has not been calibrated in a long
time and may not be working properly. Does anyone know of a product that I
could purchase and test with a known C-V curve? Perhaps an accelerometer? I
would prefer that i could use it on a probe station, and the capacitance
change should be at least 10fF.

Thanks,
Andrew O'Grady