[sdiy] CEM VCF transconductance stage difference!

[Magnus Danielson]

karl dalen skrev:
>> Magnus Danielson <magnus at rubidium.dyndns.org>
>  
>> You are correct. If all roots have the same real position,
>> they will expand out from that in the shape of a circle. The
>> sign of the feedback will control which orientation the
>> poles will have on the circle. For a 4-pole design positive
>> feedback gives poles at +/- 45 degrees and +/- 135 degrees
>> while negative feedback gives poles at 0, +/- 90 degrees and
>> 180 degrees. If the poles where not quite on mark (they
>> never are), they will gather first and then expand out as
>> expected but with a slightly skewed position and shape.
> 
> For wich filter does this apply? OTA, diode or Tr ladders?
> I imagine a well balanced OTA spread their poles differently
> then the diode and Tr?

It's not dependent on realization topology, it is part of the general 
linear analysis.

Cheers,
Magnus