Single-output dual-supply class D amplifier

摘要

An amplifier is formed by an astable multivibrator having a signal output supplying a two-state output signal to a power stage, that presents an output voltage (Vo) switching between a first and second value. The output voltage presents a duty cycle varying with the input signal (Vin) of the multivibrator. The amplifier, when connected between first and second supply lines that are symmetrical with respect to ground and are subject to supply noise, comprises a current source for generating the bias current of the astable multivibrator and supplying a current (I) that is switchable at each half cycle. The value of the current at each half cycle is proportional to the absolute value of the output voltage (Vo) of the amplifier to vary the duty cycle of the amplifier in a manner correlated the supply noise, so that the average output voltage value is zero.