Differential amplifier with adjustable common mode output voltage

摘要

A control unit automatically adjusts the supply voltage to a differential amplifier so that the amplifier has a common mode output voltage matching an input control voltage. The control unit employs circuit elements analogous to circuit elements forming the differential amplifier to generate a reference voltage in response to the supply voltage wherein the reference voltage is an estimate of the amplifier's common mode output voltage. An operational amplifier receiving the control voltage and the reference voltage as inputs, adjusts the supply voltage so the reference voltage matches the control voltage, thereby ensuring that the amplifier's common mode output voltage matches the control voltage.