High Input Impedance All-Pass Circuit

Abstract

A novel operational transconductance amplifier (OTA) based all-pass (AP) circuit exhibiting essentially infinite input impedance and facilitating non-interactive electronic control of gain and phase without disturbing the AP condition is proposed. A large amount of gain is attainable from the circuit as the scale factor is a function of the product of transfer gain (gm) of OTA and grounded resistor which can be made voltage variable. The circuit can also be made digitally programmable by controlling the bias currents of OTAs with DAC.