[sdiy] Nonlinearities in IR3109 filters

[Antti Huovilainen]

On Wed, 2 Aug 2006, Aaron Lanterman wrote:

> Interesting point about the synthi. With its diode-ladder structure, the 
> poles and the way they migrate work differently than they do in a 
> transistor-ladder or OTA-series (where the stages are buffered). So I'd 
> expect it to have different resonance characteristics. Somewhere in my notes 
> from last Fall I have worked out where the poles go.

I don't think this actually matters at all. Again, resonance happens at 
the frequency where phase shift is 180 degrees. So all you need to do is 
calculate that freq and loop gain at said freq. For small signals diode 
ladder is equivalent to cascaded RC stages without buffers between them.

Antti

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