INVERSE-SHADOW FILTERS EMPLOYING CURRENT FEEDBACK OPERATIONAL AMPLIFIER

Abstract

New configuration of voltage-mode electronically tunable shadow inverse lowpass, shadow inverse highpass ,shadow inverse bandpass, and shadow inverse bandreject filters is proposed .The 4-terminal current-feedback operational-amplifier(CFOA) and passive elements are used to build the proposed filters circuits .Inverse filters are mostly used in correcting the distortions of signals in various instrumentation ,control and communication systems caused by transmission or signal processing systems.“ A shadow filter configuration have an external amplifier added in feedback loop of the basic inverse filter and gain of this amplifier can be used to control to tune the characteristics of the resulting filter.”The parameters“of the filters can be modified over a large range without disturbing the passive and active components of the filter itself by acting only from outside filter. Unlike current-mode shadow filters which mostly requires a summing junction, this voltage mode realization does not”require summing amplifier. The passive and active sensitivities of proposed filters parameters is found to be low .The CFOA used for pspice simulation is commercial available current feedback amplifiers AD844 macromodel with ± 15 V voltage supply . The characteristics and validity of proposed biquad filters are verified by SPICE simulation.