Realization of BP active filters using UMLF structure with impedance-tapered biquads

Abstract

This paper presents the low-sensitivity realization of band-pass (BP) active resistance-capacitance (RC) filters using "uniform modified leap-frog" (UMLF) structure. Sensitivities with respect to filter passive components are investigated. It is shown how the optimization can be performed in order to achieve minimal sensitivities with relatively small values of Q-factors. Multiple-feedback-structured filters have low sensitivities to passive component tolerances, and additional sensitivity reduction of 2/sup nd/-order building biquads is achieved by the "impedance tapering" design. As an example, the sensitivity analysis, using Shoeffler sensitivity measure, was performed on a Chebyshev 8/sup th/-order BP filter. The filters were realized using UMLF and leap-frog (LF) structures, where sensitivity-optimized single-amplifier (SAB) and Sallen and key (SAK) biquads realize the 2/sup nd/-order biquads.