Texas Instruments Corporation

Peter Kavanagh

Farzad Sahandiesfanjani

Andrew Khar Boon Ong

An audio amplifier receiving a digital input audio signal and generating an output audio signal for driving a speaker includes a digital input class D amplifier configured to receive the digital input audio signal and to generate the output audio signal. The digital input class D amplifier includes a first modulator configured to receive the digital input audio signal and to generate a quasi-digital signal in n-bit, and a class D modulator configured to receive the n-bit quasi-digital signal and to generate the output audio signal, the class D modulator implementing an analog feedback loop. In some embodiments, the class D modulator is implemented using a PWM modulator. In other embodiments, the PWM modulator incorporates enhanced features to improve the output noise characteristics.

Digital input class-D audio amplifier

Clock circuits are presented for providing a clock signal using multiple reference clock signals, including a PLL operating from a PLL reference clock signal, an FLL operating from an FLL reference clock signal, and a multiplexer circuit that selectively provides up and down signals from either a PFD of the PLL or the FLL to a charge pump of the PLL according to a reference clock select signal.

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San Jose, CA, United States of America

Peter Kavanagh