Low-sensitivity, low-power fourth-order band-pass active-RC allpole filter using impedance tapering

The design of low sensitivity band-pass (BP) active resistance-capacitance low (RC) filters using impedance tapering is presented. 4/sup th/-order band-pass filters are considered. The design procedure for low-sensitivity low-pass (LP) prototype second-order class 4 Sallen and Key active-RC allpole filters, using impedance tapering, has already been published. In this paper a low-pass to band-pass (LP-BP) transformation is applied to an impedance tapered 2/sup nd/-order LP filter, and a 4/sup th/-order BP filter is constructed. The component values, selected for impedance tapering, account for the considerable decrease in sensitivity to component tolerances for the LP as well as for the BP filter. As an example, a Chebyshev 4/sup th/-order BP filter is realized, and the sensitivities are analysed. Schoeffler sensitivity measure is used as a basis for comparison, and Monte Carlo runs are performed as a double-check. A considerable improvement in sensitivity is achieved, both for the BP filter as well as well as for the original LP prototype.