Differential output stage with reduced idle current

摘要

A differential output stage utilizes four unity-gain differential amplifiers to receive a pair of input signals and to generate a differential signal. The non-inverting inputs of two of the differential amplifiers are connected together to receive one of the input signals while the outputs of the two differential amplifiers are connected to a forward node and to the inverting inputs of the two differential amplifiers. The non-inverting inputs of the remaining two differential amplifiers are connected together to receive the remaining input signals while the outputs of the remaining two differential amplifiers are connected to a reverse node and to the inverting inputs of the remaining two differential amplifiers. When an external resistor is connected between the forward node and the reverse node, the differential output stage drives a current across the external resistor in one direction when the difference between the amplitudes of the input signals is positive and drives a current across the external resistor in an opposite direction when the difference between the amplitudes of the input signals is negative.