Stability of a JFET cascoded by another JFET - diyAudio
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Old 29th April 2012, 09:32 AM   #1
diyAudio Member
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Location: Australia
Default Stability of a JFET cascoded by another JFET

In the attached simplified schematic, C2 stabilises the global feedback loop (closed by R3), but how does one predict whether the feedback loop formed by C2 around the two JFETs will be stable? I would use the same type of JFET in both positions, or the same family sorted for different Idss.
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Old 29th April 2012, 11:15 AM   #2
AndrewT is offline AndrewT  Scotland
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Join Date: Jul 2004
Location: Scottish Borders
Normally we use a high gm/low Vp device for the amp and a low gm/high Vp device for the cascode.

I don't know what effect that has on performance, nor sound.

I think you need AC coupling at the input.
regards Andrew T.
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