#### ananthesh bhat

##### Junior Member level 3

I'm starting an active filter design with in .18u technology. Its a low pass butterworth approximation with 0dB gain and with frequency tuning capability. I'm confused about selecting the topology for the implementation. There are topologies like Sallen–Key topology,Tow-Thomas biquad filter topology and Multiple feedback topology. For my filter the cut off frequencies are 1M, 5M and 10M. For these cutoff frequencies which topology will be more suitable? Is there any advantage going with a particular topology leaving the other?

In Tow-Thomas biquad topology, I have to use three opamps and thus power consumption will be more. But will I gain anything by selecting this topology?

By the way power specification for the filter is 20mW.

Please help me in this!!

Thanks.....