Parasitic insensitive, biphase switched capacitor filters realized with one operational amplifier per pole pair

Practical techniques are given for reducing the number of operational amplifiers (op-amps) in switched capacitor filters. Op-amp count is typically reduced to one op-amp per pole pair, while maintaining the insensitivity to top and bottom plate parasitics heretofore associated with one-op-amp-per-pole structures. These techniques are used to develop a parasitic insensitive single amplifier resonator and a general single amplifier biquad. Next, complete design procedures are given for these circuits. Finally, the same methods are applied to leapfrog structures, where similar op-amp savings are demonstrated.