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converting input to a Jfet

DuctDuck

Jan 26, 2013
52
Joined
Jan 26, 2013
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52
Good morning...I have some simple help with n-Jfet biasing and behavior.

I desire a highly resistive (6.0 Gohm>) input terminal to an electrometer; to capture Coulombs from the capacitor for a voltage at the Fet's gate. I have started with an open-drain amplifier (see below).

meter-input02_zps6d3e94e1.png

...thank you Digikey SchemeIt :)

Can I use -VSS to setup a drain current?

Looks like VG= -GSS, for VGS=0...ID(sat)?

But, does gate resistance increase as -Vss "increases" (more Vneg)?

Thanks in advance!

-ps. I would like to see Vneg at the capacitor before the meter starts processing
 
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