Optimum design and implementation of IIR SC filters using small-order FIR cells

A novel approach for designing infinite impulse response (IIR) switched-capacitor filters, based on the optimum allocation of poles and zeros of a transfer function, implemented by a direct-form topology using finite-impulse response (FIR) cells as basic building blocks is presented. As a consequence, low sensitivity with respect to capacitance ratio errors in both passband and stopband frequencies, low power consumption, and improved group delay response are achieved. Comparisons with classical IIR and linear-phase FIR filter designs are made. An illustrative design example including simulation and experimental results obtained with a prototype filter are provided.