A half-bridge three-level pulse width modulation (PWM) amplifier includes a prescaling unit, a PWM generator configured to convert the input signal to a three-level PWM signal having a first level, a second level and a reference level and an output stage. The prescaling unit scales an input signal according to at least one gain value to provide a scaled signal. The PWM generator varies the width of pulses having the first level and varies the width of pulses having a second level based on the scaled signal. The output stage drives an output node to a level of a first power supply voltage, a second power supply voltage or a third power supply voltage based on the three-level PWM signal. The output node is connected to a load. The magnitude of the at least one gain value compensates for variations of power supply voltages.