Power supply rejection technique for switching amplifier
Apparatus and methods greatly improve AC and, optionally, DC power supply rejection in a switching amplifier. The method broadly includes the steps of modulating the amplifier output with a compensatory signal necessary to maintain a minimum difference between an otherwise unmodulated ancillary reference switching amplifier and a static or dynamic reference.
1. A method of improving power supply rejection in a switching amplifier of the type wherein one or more output devices couple a power supply voltage to a load using a pulse-width modulator (PWM) controlled by an input signal, comprising the steps of:
providing a reference signal;
generating a compensatory signal as a function of the reference signal; and
controlling the operation of the PWM with the compensatory signal to maintain a minimum difference between the reference signal and the voltage across the load.
2. The method of claim 1 , wherein the reference signal is static or dynamic.