LOW-POWER HIGH-ORDER BAND-PASS ACTIVE-RC ALLPOLE FILTERS USING A “LOSSY ” LP-BP TRANSFORMATION

ABSTRACT: The design procedure for high-order single amplifier BP filters is presented. A method for the design of 2nd- and 4th-order band-pass (BP) active-RC filters using a modified low-pass to band-pass (LP-BP) frequency transformation, was already presented in previous works [1],[2]. It was shown 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. The Schoeffler’s sensitivity measure is used for the sensitivity analysis