A new electronically tunable first-order all-pass filter using only three NMOS transistors and a capacitor

Abstract

:In this paper, a new first-order voltage-mode (VM) all-pass filter that consists of only three NMOS transistors and a capacitor is proposed. The resonance frequency of the proposed circuit can be tuned electronically by a control current. It has high input impedance; thus, it can be easily cascaded with other VM circuits. Furthermore, it does not require any critical passive component matching conditions. Nevertheless, it does not have low output impedance. Although a floating capacitor is used in the proposed circuit, it can be easily realized with today s technologies. Ideal and nonideality analyses are performed for the proposed circuit. The behavior of the filter is verified by a number of SPICE simulations and an experimental test. The total harmonic distortion variations of the proposed circuit are found low enough