Single Amplifier, Active-RC, Butterworth, and Chebyshev Filters using Impedance Tapering

D. Jurišić (Croatia), G.S. Moschytz (Switzerland), and N. Mijat (Croatia)

Keywords

activeRC filters, singleamplifier filters,lowpower, lowsensitivity, normalized components.

Abstract

In this paper the single-amplifier active-RC filter design procedure for some common filter types, using tables with normalized filter component values, is presented. The considered filters consist of an RC ladder network in a positive feedback loop of an operational amplifier. Tables for the filter structures having equal capacitors and equal resistors were already presented [1],[2]. In this communication, we present tables for designing filters having low sensitivities to variations of passive components achieved by applying the concept of impedance tapering. The Schoeffler sensitivity measure is used as a basis for a sensitivity comparison of the filters designed with equal capacitors, equal resistors and with tapered capacitors. By using an impedance tapering design technique a considerable improvement in sensitivity is achieved. Low-pass filters of up to 6th -order are presented.

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