Multi-functional filters on differential difference operational amplifiers with a minimum number of elements

Two modifications of the second-order multifunctional active filters (ARCF) with a minimum number of passive and active elements have been developed. The proposed ARCF circuits are implemented on differential difference operational amplifiers and have extended frequency range. The basic equations and the results of computer simulation are presented, showing that the first circuit implements realize rejected filter (RF), band-pass filter (BPF) and low-pass filter (LPF), the second circuit implements - high-pass filter (HPF), BPF and LPF.