Freescale Semiconductor,inc.

Zhou Zhixu

Julian Aschieri

Gerald P Miaille

Douglas Alan Garrity

Brandt Braswell

Merit Y Hong

Youssef H Atris

An embodiment of an electronic system includes a digital audio amplifier having a continuous time modulator adapted to generate a difference signal between an audio bitstream and a feedback signal, and to perform a modulation process on the difference signal to generate an input pulse modulated signal, a class D output stage adapted to receive, quantize, and amplify the input pulse modulated signal to generate an output pulse modulated signal, and a feedback path adapted to provide the output pulse modulated signal as the feedback signal to the continuous time modulator. Another embodiment includes a class AB output stage adapted to receive and amplify an input digital audio signal to generate an analog output signal, and circuitry adapted to enable the digital audio amplifier to be configured to enable the class AB output stage and to disable the class D output stage.

Digital audio amplifiers, electronic systems, and methods

A multi-mode analog-to-digital converter includes a delta-sigma analog-to-digital converter circuit configured to receive the analog input and produce a digital bit-stream associated therewith, the delta-sigma analog-to-digital converter including at least one integrator configured to reset to an initial state in response to a reset signal A digital filter circuit is configured to receive the digital bit-stream and produce two filtered outputs derived from the digital bit-stream. During one mode (e.g., a DC mode) the delta-sigma analog-to-digital converter circuit is configured to receive the reset signal and produce the digital bit-stream for a predetermined number of clock cycles, and the digital output corresponds to the first filtered output. In another mode (e.g., an AC mode), the delta-sigma analog-to-digital converter is configured to continuously produce the bit-stream, and the digital output corresponds to the second filtered output.

Methods and apparatus for a multi-mode analog-to-digital converter

A method and apparatus are provided for operating a feedback network (). The method and apparatus operate to combine () a feedback signal (I) and an incoming signal (V) to generate an adjusted signal (I) at an input node of an amplifier element (); amplifying the amplifier input signal in the amplifier element to produce an amplifier output signal (V) at an output node of the amplifier element; processing the amplifier output signal according to a feedback operation () to generate the feedback signal (I); and providing an assist current (, I) to the output node of the amplifier element, separate from an output current provided by the amplifier element.

System and method for operating a feedback network

A method and apparatus are provided for reducing the size and power of cyclic analog-to-digital converter (ADC) conversion circuits. During each cycle, the ADC conversion circuit generates a plurality of bits. The improved ADC includes a scaling/reference circuit having a single operational amplifier which operates in a reference generation mode and an analog multiplexing mode during generation of the first bit and operates in the analog multiplexing mode during generation of the subsequent bits.

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Gilbert, AZ, United States of America

Zhou Zhixu