Cirrus Logic Inc.

Johann Guy Gaboriau

John L Melanson

Xiaofan Fei

Lingli Zhang

Lei Zhu

Jason Powell Rhode

Amar Vellanki

Tejasvi Das

Xin Zhao

Zhong You

Wai-Shun Shum

Dan Shen

Eric Walburger

Leyi Yin

Steven Green

Vamsikrishna Parupalli

Alan Mark Morton

Eric Jerome King

Siddharth Maru

Matthew Beardsworth

Wilson E Taylor, Jr

Brian David Trotter

Melvin L Hagge

Shahrzad Naraghi

Joseph Jason Welser

Vikrant Arumugam

Eric J Swanson

Ramin Zanbaghi

Christian Larsen

Lei Ding

Vishnu Shankar Srinivasan

Ku He

Gregory Charles Yancey

Prashanth Drakshapalli

Thomas H Hoff

Aaron J Brennan

Luke Lapointe

Chang Yong Kang

Venugopal Choukinishi

Eric Clay Gaalaas

Aiman Alhoussami

David M Olivenbaum

Jiandong Jiang

Xaiofan Fei

Gautham Sivasankar

Mehul Marolia

Randy Boudreaux

Evan Logan Marchman

Wei-Shun Shum

A system may include a resistive-inductive-capacitive sensor, a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor, and a filter communicatively coupled to the measurement circuit. The measurement circuit may be configured to measure phase information associated with the resistive-inductive-capacitive sensor and based on the phase information, determine a displacement of a mechanical member relative to the resistive-inductive-capacitive sensor. The filter may be configured to isolate changes to the displacement which are significantly slower than an expected change to the displacement in response to a human interaction with the mechanical member.

Detecting and adapting to changes in a resonant phase sensing system having a resistive-inductive-capacitive sensor

A single integrated circuit may include a signal path configured to generate an output signal from an input signal, wherein the signal path includes an amplifier configured to drive the output signal, a direct-current-to-direct-current (DC-DC) power converter having a power inductor integrated in the single integrated circuit and configured to generate a supply voltage to the amplifier from a source voltage to the DC-DC power converter, and control circuitry for controlling operation of converter switches of the DC-DC power converter in order that the supply voltage tracks at least one among the input signal and the output signal.

On-chip inductor with audio headphone amplifier

A method for calibrating gain in a multi-path subsystem having a first processing path, a second processing path, and a mixed signal return path, may include low-pass filtering an input signal and a mixed signal return path signal generated from the input signal at subsonic frequencies to generate a filtered input signal and a filtered mixed signal return path signal and tracking and correcting for a gain difference between the first processing path and the second processing path based on the filtered input signal and the filtered mixed signal return path signal.

Tracking and correcting gain of open-loop driver in a multi-path processing system

A differential output current digital-to-analog converter (IDAC) circuit may include a delta-sigma modulator configured to receive a digital input signal, a control circuit responsive to the delta-sigma modulator configured to perform a DAC decode operation, a plurality of DAC elements responsive to the DAC decode operation, the plurality of DAC elements configured to, in concert, generate a differential output current signal based on the digital input signal to a load coupled to a pair of output terminals of the IDAC, and an output impedance coupled between the pair of output terminals such that the output impedance is in parallel with the load.

Current digital-to-analog converter with high-impedance output

A method may include applying an excitation signal to a capacitor of the capacitive sensor which causes generation of a modulated signal from an input signal indicative of a variance in a capacitance of the capacitor, detecting the modulated signal with a detector to generate a detected modulated signal that has a phase shift relative to the excitation signal, demodulating the detected modulated signal into an in-phase component and a quadrature component using a reference signal, nullifying the quadrature component by setting a phase of the reference signal relative to the excitation signal to compensate for the phase shift, and outputting the in-phase component as an unmodulated output signal representative of the capacitance.

Capacitive sensor including compensation for phase shift

A system may include a current digital-to-analog converter (IDAC) configured to convert a digital input signal into an output current signal and a switched-mode power supply configured to provide electrical energy in the form of a supply voltage to the IDAC for operation of the IDAC, the switched-mode power supply configured to track a voltage signal derived from the digital input current signal and generate the supply voltage based on the voltage signal and a voltage headroom above the voltage signal.

Using a tracking switched-mode power supply to increase efficiency of a current digital-to-analog converter-based output stage

A differential output current digital-to-analog (IDAC) circuit may include a delta-sigma modulator configured to receive a digital input signal, a control circuit responsive to the delta-sigma modulator configured to perform a DAC decode operation, a plurality of DAC elements responsive to the DAC decode operation, the plurality of DAC elements configured to, in concert, generate a differential output current signal based on the digital input signal to a load coupled to a pair of output terminals of the IDAC, and a plurality of warming switches, each warming switch coupled to a respective bias transistor of a respective DAC element of the plurality of DAC elements, wherein the control circuit may further be configured to selectively control each such warming switch in order to selectively de-bias and bias a respective bias transistor of such warming switch when a respective DAC element of the respective bias transistor is output-disabled from generating the differential output current signal.

Current digital-to-analog converter with warming of digital-to-analog converter elements

A method for measuring a capacitive sensor output may include applying an excitation signal to a capacitor of the capacitive sensor which causes generation of a modulated signal from a baseband signal, wherein the excitation signal is of a carrier frequency which is higher than frequency content of the baseband signal, demodulating the modulated signal to generate an intermediate signal representative of a capacitance of the capacitor wherein the demodulating is based, at least in part, on the excitation signal, converting the intermediate signal into a pulse-density modulated output signal with a pulse-density modulator, and shaping a noise transfer function of the pulse-density modulator to have an approximate zero at the carrier frequency.

Reducing noise in a capacitive sensor with a pulse density modulator

A system may include a first resistive-inductive-capacitive sensor, a second resistive-inductive-capacitive sensor, and a measurement circuit communicatively coupled to the first resistive-inductive-capacitive sensor and the second resistive-inductive-capacitive sensor and configured to measure first phase information associated with the first resistive-inductive-capacitive sensor, measure second phase information associated with the second resistive-inductive-capacitive sensor, and based on the first phase information and the second phase information, determine a displacement of a mechanical member relative to the first resistive-inductive-capacitive sensor.

Use of reference sensor in resonant phase sensing system

In accordance with embodiments of the present disclosure, an apparatus may include a signal path comprising a closed-loop analog pulse width modulator having a forward signal path and a feedback path, a variable resistor coupled to an output of the closed-loop analog pulse width modulator, and a control circuit configured to modify the variable resistor in order to modify an output impedance outside of the feedback path of the closed-loop analog pulse width modulator responsive to a condition for switching between a high output impedance mode and a low output impedance mode of the closed-loop analog pulse width modulator or vice versa.

Variable output resistance in a playback path with closed-loop pulse-width modulation driver

A digital delta-sigma modulator may include a loop filter having a loop filter input configured to receive an input signal and generate an intermediate signal responsive to the input signal and a multi-bit quantizer configured to quantize the intermediate signal into a quantized output signal which is fed back as an input to the loop filter. The multi-bit quantizer may further be configured to operate in at least two modes comprising: (a) a normal mode in which, for each sample of the intermediate signal, the multi-bit quantizer generates a corresponding sample having a value selected from a set of a plurality of quantization levels; and (b) a code suppression mode in which, for each sample of the intermediate signal, the multi-bit quantizer generates a corresponding sample having a value selected from a subset of the set of a plurality of quantization levels.

Increased noise performance using quantizer code suppression

A system may include a filter configured to receive a digital audio input signal quantized at between two and 257 quantization levels and sampled at at least 500 kilohertz, the filter further configured to perform filtering on the digital audio input signal to generate a filtered digital audio input signal, the filter having a selectable variable group delay, a digital-to-analog converter configured to receive the filtered digital audio input signal and convert the filtered digital audio input signal into an equivalent analog audio input signal, and a driver configured to receive the equivalent analog audio input signal and drive an analog audio output signal to a transducer.

Low-latency audio output with variable group delay

In a signal path comprising an analog path portion configured to operate in a plurality of output impedance modes including a high impedance mode with a first impedance and a low impedance mode with a second impedance, and a digital path portion having a variable digital gain and configured to convert a digital input signal and into an analog signal provided to the analog path portion, a method may include responsive to a condition for switching between the high impedance mode and the low impedance mode or vice versa, transitioning the output impedance continuously or in a series of steps between the first impedance and the second impedance or vice versa and, contemporaneously with transitioning the output impedance, transitioning the variable digital gain continuously or in a series of steps such to maintain a substantially constant overall path gain for the signal path remains substantially constant during transition.

Variable output resistance in a playback path with open-loop pulse-width modulation driver

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Austin, TX, United States of America

Johann Guy Gaboriau