[sdiy] Modelling the LM13700 bias input in LTSpice

sleepy_dog at gmx.de sleepy_dog at gmx.de
Sun Aug 13 14:43:36 CEST 2017

I don't recall *exatcly* where I found this, I think in the depths of 
the LTspice yahoo group.
Uploaded here (they'll delete it in 1..2 weeks I think, so If anyone 
gets from vacation and reads this then, sorry ;) )

I used it in some tests and it basically worked as I (an electronics 
layman picking up some things here and there)
expected. *Except* exactly when doing anything with the diode bias pin. 
But perhaps I just haven't understood properly how to use it exactly, 
with regards to what that does to the overall behavior of the OTA except 
"make it more linear".
Maybe you have more "luck" with that ;)


Am 13.08.2017 um 12:29 schrieb Tom Wiltshire:
> Hi All,
> If I want to do some experiments in simulation, using different current sources to feed the pin1/16 bias input of the LM13700, how should I model the 13700’s input?
> I don’t particularly need to model the whole chip, but I need the input to respond realistically. If modelling the whole chip is the best way, where do I find a good LM!34700 model? I’ve read various places that the input is two diode drops above the negative power rail, and other places that it’s a diode drop above ground. And what about its impedance? What does that look like?
> Thanks,
> Tom
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> Synth & Stompbox DIY
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