Two-CFOA-grounded-capacitor first-order all-pass filter configurations with ideally infinite input impedance

Abstract

Recently, Yuce, Verma, Pandey and Minaei presented two interesting current feedback operational amplifier (CFOA)-based first-order all pass filter (APF) configurations employing a single grounded capacitor (GC). Their first circuit employs only two CFOAs (along with five resistors) but does not have ideally infinite input impedance; the second circuit although does possess ideally infinite input impedance but requires three CFOAs (along with five resistors). In this paper, we present six new GC-APFs which employ only two CFOAs and yet provide infinite input impedance with a reduced number of only three/four resistors than the quoted earlier circuits. A non-ideal analysis of all the proposed circuits has been carried out and the workability and utility of the proposed circuits has been corroborated by the SPICE simulation and hardware implementation results using AD844-type IC CFOAs. This paper, thus, adds a number of interesting alternatives to the CFOA-based first-order APFs presented in the mentioned earlier work.