[sdiy] Modelling the LM13700 bias input in LTSpice

[Tom Wiltshire]

Thanks Steve. That seems to do the trick, although I still don’t know what the details are.

When I said “bias input”, I mean the Iabc control input, not the diode bias. I’m not using the diode bias in this circuit, so currently that’s not an issue.

Thanks,
Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 13 Aug 2017, at 13:43, sleepy_dog at gmx.de wrote:
> 
> 
> 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 ;) )
> https://we.tl/Vpnte54SiJ
> 
> 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 ;)
> 
> Steve
> 
> 
> 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
>> 
>> 
>> ==================
>>        Electric Druid
>> Synth & Stompbox DIY
>> ==================
>> 
>> 
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