Cheby Cheby Cheby.

[Don Tillman]

I can imagine a Cheby VCF module...  6 poles built with 3 2-pole state
variable filter circuits strung together in series.  You'd probably
need at least 6 poles for the effect to be worth the trouble.  A
voltage-controlled frequency input would tune the state variable
filters together.  A voltage-controlled Cheby input would map directly
to the epsilon in the Cheby transfer function, so you could have 0
volts for a Butterworth response (epsilon = 0), 1 volt for a medium
Cheby response with 3dB ripple (epsilon = 1) and 5 volts for an
extreme Cheby response with 14 dB ripple (epsilon = 5).  This input
would need to tune the frequencies and Qs of the individidual state
variable filters after some nonlinear processing.  The nonlinear
processing would not have to be super accurate.

Extra points for implementing inverse Chebys with negative epsilons.
:-) 

  -- Don

-- 
Don Tillman
Palo Alto, California, USA
don at till.com
http://www.till.com