Re: JFET Common Source DC Amplifier Temperature Compensation

On Tue, 20 Nov 2007 15:38:04 -0800, D from BC
<myrealaddress@xxxxxxxxx> wrote:

On Tue, 20 Nov 2007 15:30:40 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx> wrote:

[snip]

Sort of like this...

http://analog-innovations.com/SED/DfromBC-Bias.pdf

Not dead-on, but close... exact solution is left as an exercise for
the student ;-)

...Jim Thompson

Yup...I think that's where I'm headed..

Maybe call J2 a 'reference amp'. Where J2 is a reference circuit.
Relative to J2 drift, compensate to maintain J1's bias point.
Something like that... :P


Nice.. You did a temp sweep.

Heck...I don't even know if I can trust LT's JFET models and I haven't
spotted yet if I can do a temp sweep in LTSpice.

Sure you can. Mikey did a good job with LTspice.


I'd say 90% of circuits I've seen use Rs in JFET linear circuits.
Without Rs...it's interesting to see the performance of the
alternatives. :)


D from BC

If you're really trying to make a comparator rather than a linear
amplifier, you might experiment with current source loads (hint, hint
;-)

...Jim Thompson
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