Patent ID: 6297693
Filing Date: 2001-10-02
Classification: H03C,H03F

Abstract:
A self oscillating class D amplifier synchronized to an external clock comprising:an integrator with a summing input for receiving inputs from an audio signal source and analog and digital feedback signals of the amplifier output;a pulse width modulator for receiving the output of the integrator and a feedback signal representative of an output of the amplifier and generating a series of output pulses where the width of the pulses is proportional to the amplitude of the input audio signal;a bridge comprising an upper mosfet and a lower mosfet;level shift and gate drive circuitry coupled to the output of the pulse width modulator and to the gates of the mosfets for shifting the output level of the pulses and for driving the gates of the mosfets;a digital output terminal coupled to the mosfets and an inductor and low pass filter coupled to the digital output for converting the digital output into an analog signal for driving a speaker; anda transmission gate coupled to the pulse width modulator for selectively connecting an external clock signal to the pulse width modulator for controlling the output frequency of the pulse width modulator in accordance with the external clock signal.