A low-pass biquad derived filter realization

A biquad derived structure employing two Norton (current differencing) amplifiers is presented which requires the minimum number of components. Transfer characteristics of the form K/SUB 1//D(S) and K/SUB 2/(S+/spl omega//SUB n//Q)/D(S) with D(S)=S/SUP 2/+/spl omega//SUB n/S/Q+/spl omega//SUB n//SUP 2/ are realized. Biasing constraints are of major importance in the detailed realization and a typical circuit design is presented along with a discussion of its performance, which is compared with that of others.