A new approach to the design of bilinear-LDI switched-capacitor filters having low passband sensitivity

Abstract

An approach to the design of low-sensitivity switched-capacitor (SC) filter is described. In this approach, the continuous-time reference transfer function is decomposed into a sum of two individual functions, and each function is realized as the transfer function of a voltage-divider network consisting of a resistance as its series arm and a reactive impedance as its shunt arm. The bilinear-LDI (lossless discrete integrator) design technique is applied to the SC realization of the two voltage-divider networks. These individual realizations are combined to form the SC realization of the overall filter. The resulting filter requires n+1 operational amplifiers (OAs) for its realization, where n is the order of the reference transfer function. For illustration purposes, the proposed approach is applied to the bilinear-LDI SC design of a practical sixth-order elliptic bandpass filter. It is shown that the filter exhibits low sensitivity to dominant-pole OA effects. >