[sdiy] Bandpass Filter Recommendations

[Scott Juskiw]

I'm working on a programmable filter bank and am asking the group for  
recommendations on a suitable bandpass filter. The filter requirements  
are:

1. voltage controlled frequency
2. voltage controlled resonance
3. voltage controlled gain
4. analogue circuit

Some solutions I've come up with:

1. state variable filter
2. cascaded lowpass/highpass filters (using cascaded OTA stages)

#1 is relatively easy but I'm less than thrilled with the 6db/oct  
slopes. #2 seems to be better for my needs since I can get 12 db/oct  
slopes.

Are there any other filter topologies that anyone can recommend?  
Hopefully something that won't require 400 components per filter since  
I'd like to have a bank of these on one PCB. But maybe that's asking  
for too much. I would also consider a digital filter solution, if it  
would be easier to build and if (big IF) I could figure out how to do  
it digitally.

Thanks