A voltage-mode first order allpass filter based on VDTA

Abstract

This article presents a new voltage-mode first order allpass filter (APF) employing voltage differencing transconductance amplifier (VDTA). The advantages of the circuit are that: the circuit description is very compact, consists of merely a VDTA and a capacitor: the phase shift can be electronically adjusted by current bias: it provides the lower THD of the output signal. Without any component matching conditions, the proposed circuit is very appropriate to further develop into an integrated circuit. Moreover, the proposed APF can provide the output current with high output impedance without modification of the circuit topology. The PSpice simulation results are depicted. The given results agree well with the theoretical anticipation. The maximum power consumption is 400µW at ±1.25V power supplies.