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.