Three new CFOA-based SIMO-type universal active filter configurations with unrivalled features

Abstract

In this paper, three new single-input-multiple-output (SIMO)-type second order universal active filter (UAF) configurations, each employing only four current feedback operational amplifiers (CFOA), are proposed which offer the following attractive features simultaneously: (i) realisability of all the five generic filter functions viz. low pass filter, high pass filter, band pass filter, band reject filter and all-pass filter from the same configuration (ii) tunability of the pole frequency (ω0), quality factor (Q0)/bandwidth (BW) in all the five responses (iii) tunability of gain (H0) in most of the responses (iv) ideally infinite input impedance and ideally zero output impedance in all the cases and (v) employment of two grounded-capacitors, as preferred for IC implementation. To the best knowledge of the authors, these features of the presented new circuits are unrivalled by the other SIMO-type CFOA-based UAF biquads published earlier as none of them provide all the above mentioned advantages simultaneously while using only four CFOAs and two grounded capacitors. The workability of the proposed UAF structures has been demonstrated by SPICE simulation results as well as the experimental results using the commercially available AD844-type IC CFOAs.