Cirrus Logic Inc.

Bhupendra Singh Manola

Pradeep Dhananjay

John L Melanson

Tejasvi Das

Bruce Eliot Duewer

Chandra Prakash

Willem Zwart

Ramya Balasundaram

An integrated circuit having multiple switched-capacitor delta-sigma data converter circuits includes compensation for voltage reference error due to leakage current that causes reference voltage droop. The reference filter capacitor terminal voltage is maintained by periodic connection to the reference feedback capacitor(s) that are alternately connected to a voltage reference buffer, and the leakage into the reference feedback capacitor networks of disabled converter circuits causes reference voltage droop. The compensation is either determined from the number of converter circuits that are disabled, or from an error between the filter capacitor voltage and a separate voltage reference, and may be applied by adjusting a resistance selectively coupled between the voltage reference buffer output and the filter capacitor, feedback applied to the voltage reference buffer or its input source. Alternatively, or in combination, correction may be applied to the output of the active converters by digital adjustment of output values.

Gain error reduction in switched-capacitor delta-sigma data converters sharing a voltage reference with a disabled data converter

An amplifier may include a main signal path having a plurality of stages compensated by feedback elements, the plurality of stages comprising an output stage configured to receive electrical energy from a power supply and an auxiliary path independent of the main signal path and comprising an output stage compensation circuit configured to generate a compensation current proportional to noise present in the power supply and apply the compensation current to cancel a power supply-induced current present in at least one of the feedback elements.

Amplifier with auxiliary path for maximizing power supply rejection ratio

An apparatus may include a digital-to-analog converter configured to convert a digital audio input signal into a differential analog input signal with a substantially non-zero common-mode voltage, an amplifier configured to receive the differential analog input signal and generate at an amplifier output a ground-centered output signal from the differential analog input signal, a clamp configured to selectively couple and decouple the amplifier output to a ground voltage, and a controller configured to control the clamp to selectively couple and decouple the amplifier output to a ground voltage responsive to transitions between power states of a device comprising the apparatus and control the differential analog input signal generated by the digital-to-analog converter in order to minimize a level transition current through an output load coupled to the amplifier output during transitions between the power states.

Reducing audio artifacts in an amplifier during changes in power states

An apparatus may include a delta-sigma modulator for quantization noise shaping of a digital signal, a digital-to-analog converter configured to generate an analog signal from the digital signal, and an amplifier configured to amplify the analog signal and powered from a charge pump, wherein the charge pump is configured to operate at a switching frequency approximately equal to a zero of a modulator noise transfer function of the delta-sigma modulator, such that the impact of charge pump noise on a total harmonic distortion noise of the apparatus is minimized.

Controlling noise transfer function of signal path to reduce charge pump noise

A system comprises a first module and a second module, connected by a transmission line comprising first and second wires. The first module includes common mode voltage circuitry, for imposing a common mode voltage onto the first and second wires. The first module includes signal generation circuitry, for generating a signal voltage in response to first data, and for imposing the signal voltage as a differential signal onto the first and second wires during periods when the first module has first data to transmit. The second module includes current generation circuitry, for generating a signal current in response to second data, and for injecting the signal current as a differential current onto the first and second wires during periods when the second module has second data to transmit. The first module includes respective resistances connected to the first and second wires. The first module includes a first detector for obtaining first output data based on voltages across the resistors resulting from the signal current injected by the current generation circuitry of the second module; and the second module includes a second detector for obtaining second output data based on differential signal imposed by the signal generation circuitry of the first module.

Growing community of inventors

Austin, TX, United States of America

Bhupendra Singh Manola