Unity-gain buffer based switched-capacitor biquads

Switched-capacitor (SC) biquads are basic second order building blocks of higher order cascaded sampled data filters. Generally, the active elements in these biquads are op-amps. There have been a few attempts to build buffer-based biquads, however, there are some difficulties which must be taken into account; relatively large buffer DC offset voltage (usually the gate-to-source voltage of the input device); buffer gain error of the order of 0.01-0.001; and sensitivity to parasitic capacitance at buffer inputs since these inputs are not at virtual ground potential. The authors present two buffer-based biquads which are offset and gain error compensated and have low sensitivity to parasitic capacitance