Novel mixed-mode universal biquad configuration

Although a variety of CFOA-based biquads have been known in the literature, any CFOA-based circuit capable of realising universal biquad filters in all the four possible modes i.e. voltage-mode, current-mode, trans-admittance-mode and trans-impedance-mode, has not been reported in the literature so far. In this paper, a novel configuration has been presented, which realises all the five generic filter functions (namely, low-pass, band-pass, high-pass, notch and all-pass) from the same circuit in all the four possible modes, employing only four-Current feedback operational amplifiers (CFOA) along with two grounded-capacitors as desirable for Integrated Circuit implementation. The workability of the circuit has been confirmed by hardware implementation based on AD844 type CFOAs.