An amplifier generates a tri-level output signal in response to an input
signal that is pulse-width modulated. The amplifier is filterless and DC
free. A control block supplies a multitude of pulse-width modulated (PWM)
signals in response to the received digital input signal. A pair of the
PWM signals are applied to the signal generator which in response
supplies a third signal to the integrator. The integrator integrates the
third signal in accordance with a feedback signal.