Single-output dual-supply class D amplifier

摘要

An amplifier (70) is formed by an astable multivibrator (2) having a signal output (15, 19) supplying a two-state output signal to a power stage (3), the output (35) of which 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 (70) is connected between a first and second supply line (Vcc, -Vcc) symmetrical with respect to ground (13) and subject to supply noise ( DELTA V), and comprises a current source (71) for generating the bias current of the astable multivibrator and supplying a current (I) switchable at each half cycle; the value of the current at each half cycle being proportional to the absolute value of the output voltage (Vo) of the amplifier, so as to vary the duty cycle of the amplifier in a manner correlated with the supply noise, so that the average output voltage value is zero. <IMAGE>