Cirrus Logic Inc.

Marvellworld Trade Ltd.

Marvell International Limited

Ruoxin Jiang

Rahul Singh

Zhaohui He

Gregory Takeo Uehara

John L Melanson

Brian Taylor Brunn

Rinaldo Castello

Alessandro Venca

Fernando De Bernardinis

Chao Yang

Marc Leroux

Xiaodong Wang

Eric J Swanson

John Christopher Tucker

Lingli Zhang

Zhong You

Graeme G Mackay

Prashanth Drakshapalli

Stephen Timothy Hodapp

Anindya Bhattacharya

Theodore M Burk

Hasnain Akram

Thirumalai Rengachari

Roderick D Holley

Sakkarapani Balagopal

Frank Cheng

Rod Holley

Marck Leroux

A method for determining if an inductor coupled to a switching network has been electrically shorted may include applying a voltage across the inductor for a predetermined period of time, controlling an impedance in an electrical path of a voltage source generating the voltage and the inductor, sensing an inductor current through the inductor, comparing the inductor current with a predetermined current threshold, and determining whether the inductor has been electrically shorted based on the inductor current, the predetermined current threshold, and the predetermined period of time.

Short detection for inductive switching converters

A Class-D amplifier that includes a driver stage operable in a plurality of modes having different respective output impedances, a loop filter having an output, and a circuit configured to sense a current at a load of the Class-D amplifier, determine, based on the sensed current, an IR drop for a respective output impedance of the driver stage, and add the IR drop to the loop filter output to compensate for the respective output impedance of the driver stage to reduce distortion.

Distortion reducing variable output impedance class-D amplifier

A Class-D amplifier includes a plurality of power rails, a quantizer, and a driver stage. The quantizer and the driver stage have a combined gain. For each power rail of the plurality of power rails, the Class-D amplifier senses a voltage value for the power rail and determines a ramp amplitude based on the sensed voltage value. The Class-D amplifier concurrently switches from the driver stage using a first power rail to a second power rail of the plurality of power rails and switches from the quantizer using the ramp amplitude associated with the first power rail to using the ramp amplitude associated with the second power rail so that the combined gain is constant.

Class-D amplifier with multiple power rails and quantizer that switches used ramp amplitude concurrently with switch in used power rail

An apparatus measures a speaker impedance. A DAC converts a known digital input signal to an audio frequency first analog voltage signal. Resistors with known resistance attenuate the first analog voltage signal to generate a current. The known resistance effectively determines the current because the known resistance is high relative to the speaker impedance. The current is sourced into the speaker to generate a second analog voltage signal. The known resistance is sufficiently high to cause the second analog voltage signal to be inaudible as transduced by the speaker. An amplifier amplifies the second analog voltage signal with a known gain to generate a third analog voltage signal. An ADC converts the third analog voltage signal to a digital output signal. A processing element calculates the impedance of the speaker proportional to the digital output signal based on the known digital input signal, the known resistance, and the known gain.

Apparatus and method for measuring speaker transducer impedance versus frequency with ultralow inaudible signal

A Class-D amplifier having a low power dissipation mode includes first and second independent output stages that receive respective first and second level power supply voltages for driving a load coupled to the amplifier output during respective first and second operating modes. Bypass switches are controllable to disconnect the second output stage from the output during the first operating mode and to connect the second output stage to the output during the second operating mode. The operating modes are selected based on the amplifier output power level. First and second independent pre-driver stages receive the respective first and second level power supply voltages for driving the respective first and second independent output stages. During the second operating mode the first pre-driver stage is placed into a low power dissipation state and during the first operating mode the second pre-driver stage is placed into a low power dissipation state.

Class-D amplifier with multiple independent output stages

In a Class-D amplifier, first/second ratios and first/second RC time constants are sequentially matched by trimming. An integrator is coupled to differential first/second paths. The first/second ratios are of a feedback resistor to an input resistor in the first/second paths. R's of the first/second RC time constants are the resistors of the first/second matched ratios. C's of the first/second RC time constants are integrating capacitors in the first/second path. For each of multiple power rails, a ramp amplitude is determined based on a sensed voltage. Concurrently, the driver stage is switched from first to second power rails and quantizer switched from first to second ramp amplitudes to achieve constant combined quantizer/driver stage gain. Based on a sensed load current, an IR drop is determined for a respective output impedance of the driver stage and added to a loop filter output to compensate for the respective output impedance.

Low power dissipation high performance Class-D amplifier

In accordance with embodiments of the present disclosure, an apparatus for measuring acceleration may include a spring-mounted mass, a positional encoder configured to measure a position of the spring-mounted mass and output one or more signals indicative of a sine and a cosine of the position, a driver to set and maintain an oscillation of the spring-mounted mass, and a decoder configured to process the one or more signals to calculate an acceleration of the spring-mounted mass.

Systems and methods for determining acceleration based on phase demodulation of an electrical signal

In one embodiment a heating mechanism is provided with an integrated circuit for testing and calibration purposes. During production testing, heating elements may be activated in order to quickly bring an integrated circuit up to operating temperature for temperature testing or calibration. Once the operating test temperature has been reached, the circuit can be quickly and easily tested to show it is operable within the design temperature range and/or to obtain calibration data to correct for temperature drift. Calibration data may be used to create correction data, which may be stored within the integrated circuit. During normal operation, the correction data may be used to compensate for variations in operation due to temperature.

Bandgap with thermal drift correction

In one embodiment, an apparatus includes an upconversion unit configured to upconvert a baseband signal to a radio frequency (RF) signal. A plurality of baluns for a plurality of wireless bands are provided. Multiplexing circuitry is coupled to the plurality of baluns where the upconversion unit is coupled to each balun through the multiplexing circuitry. The multiplexing circuitry is configured to multiplex the radio frequency signal from the upconversion unit to one of the plurality of baluns based on a wireless band being used.

Transmit architecture for wireless multi-mode applications

A delta-sigma modulator includes two integrators. One of the two integrators is lossy. The lossy integrator may be a continuous-time integrator, or a discrete-time integrator. Use of the lossy integrator maintains stability of the delta-sigma converter over a relatively wide range of input signals.

Apparatus and methods for safe-mode delta-sigma modulators

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Austin, TX, United States of America

Ruoxin Jiang