Low-power high-order band-pass active-RC allpole filters using a "lossy" LP-BP transformation

The design procedure for high-order single amplifier BP filters is presented. A method for the design of 2/sup nd/- and 4/sup th/-order band-pass (BP) active-RC filters using a modified low-pass to band-pass (LP-BP) frequency transformation, has already been presented in previous works. It showed that a BP filter could be realized simply by the substitution of resistors and capacitors of the ladder in a low-pass (LP) prototype filter, by serial and parallel RC circuits. Such a substitution results from a so-called "lossy" LP-BP transformation. In this paper, the design procedure is extended to higher-order BP filters, such as 6th- and 8th-order. The design procedure is simple, and the closed-form design equations are presented. Furthermore, it is shown that "impedance tapering" decreases sensitivities to component tolerances for the LP prototype, as well as for the resulting BP filter. Schoeffler´s sensitivity measure is used for the sensitivity analysis.