A NEW ELECTRONICALLY-TUNABLE ACTIVE-ONLY UNIVERSAL BIQUAD

Abstract

A number of configurations for realizing voltage-mode (VM) biquads using op-amps and OTAs have been presented in the literature, however, none of these provide the following desirable properties simultaneously: (i) realizability of all the five standard filters (namely; low pass, high pass, band pass, band stop and all pass), (ii) tunability of all the three filter parameters (namely; ω0, bandwidth or Q0 and gain) and (iii) not requiring any realization condition in any of the five filter responses. This paper presents a new configuration which does possess all the above mentioned desirable properties simultaneously while using only two internally-compensated type op-amps and a reasonable number of OTAs. The workability of the new configuration has been demonstrated by SPICE simulations based upon CMOS Op-amp and CMOS OTAs.