New universal biquads employing CFOAs

Four new single-input-multi-output-type universal biquad filters using current-feedback operational amplifiers (CFOAs) are presented, which realize all the five standard filter functions (namely, low-pass, bandpass, high-pass, notch, and all-pass) from the same configuration, provide tunability of the various filter parameters in all the five responses, and offer a resistive or ideally infinite input impedance while employing only four CFOAs and two grounded capacitors as preferred for integrated circuit implementation. The workability of the new biquads has been verified by hardware implementations and SPICE simulations based upon AD844-type CFOAs, and some sample results are presented. Index Terms--Analog circuit design, biquad filters, current-feedback operational amplifiers (CFOAs).