Cirrus Logic Inc.

Daniel John Allen

Aniruddha Satoskar

Edmund Mark Schneider

John L Melanson

Anand Ilango

John Christopher Tucker

Seyedeh Maryam Mortazavi Zanjani

Ramin Zanbaghi

Saurabh Singh

Tejasvi Das

Scott Allan Woodford

Ammisetti Prasad

Bharath Kumar Thandri

Thuan Luong Nguyen

Eric J Swanson

Cory Jay Peterson

Aaron J Brennan

Shatam Agarwal

Alvin Chuck Storvik

Akshay Godbole

Jeffrey Donald Alderson

Xiaofan Fei

Lingli Zhang

Emmanuel A Marchais

Eric Kimball

Ku He

Dylan Alexander Hester

Bhoodev Kumar

Gong Tom Lei

Dan Shen

Christophe J Amadi

Brian Parker Chesney

Jason Lee Wardlaw

Vivek Jindal

Christophe Jean-Francois Amadi

Siladitya Dey

Harish Raghavan

Aaron Brennan

Thuan L Nguyen

Anand S Ilango

A system may comprise a high-pass filter having an input for receiving an input signal, an output for generating an output signal, a capacitor coupled between the input and the output, a switched-capacitor resistor coupled between the output and a reference voltage, and control circuitry configured to control the reference voltage to cancel current leakage into a circuit coupled to the output. The input, the output, the capacitor, and the switched-capacitor resistor may be arranged to generate the output signal as a high-pass filtered version of the input signal and the high-pass filter may be configured to operate in a plurality of modes comprising at least a high-impedance mode and a low-impedance mode in which the resistance of the switched-capacitor resistor is significantly smaller than the resistance when in the high-impedance mode. A system may include a plurality of processing paths having a first path configured to generate a first digital signal based on an analog input signal and a second path configured to generate a second digital signal based on the analog input signal, the second path having a high-pass filter for filtering the analog input signal prior to the analog input signal being processed by the remainder of the second path, and the high-pass filter having a corner frequency. Control circuitry may be configured to determine frequency-dependent weighted proportions of the first and second digital signals to be combined into an output digital signal based on a characteristic of the analog input signal. Frequency-dependent weighted proportions may be such that the digital output signal includes spectral content of the first digital signal below the corner frequency to account for spectral content of the second digital signal below the corner frequency being filtered. A system may include an input for receiving an input signal, an output for generating an output signal, a capacitor coupled between the input and the output, a variable resistor coupled to the output and having a plurality of modes including a first mode in which the variable resistor has a first resistance and a second mode in which the variable resistor has a second resistance, and control circuitry configured to determine a difference between the input signal and the output signal and switch between modes of the plurality of modes when the difference is less than a predetermined threshold.

Multi-path analog system with multi-mode high-pass filter

A system may include a plurality of processing paths and a controller. The processing paths may include a first processing path configured to generate a first digital signal based on an analog input signal and one or more other processing paths each configured to consume a smaller amount of power than the first processing path, and each configured to generate a respective digital signal based on the analog input signal, wherein one of the other processing paths has a noise floor based on fidelity characteristics of the analog input signal or subsequent processing requirements of a digital output signal generated from at least one of the first digital signal and the respective digital signals. The controller may be configured to select one of the first digital signal and the respective digital signals as the digital output signal of the processing system based on a magnitude of the analog input signal.

Multi-path digitation based on input signal fidelity and output requirements

An analog conditioning circuit and a corresponding method for processing an analog input signal provide a conditioned analog signal for input into an analog processing circuit. The analog conditioning circuit comprises a main signal path between an input for receiving the analog input signal and an output for outputting the conditioned analog signal, wherein the transfer function of the main signal path is constrained by a transfer function requirement associated with the analog processing circuit; and a feedforward signal path comprising a first filtering block configured to attenuate desired frequencies of a first signal derived from the analog input signal to provide a filtered analog signal; wherein the feedforward signal path is configured to input the filtered analog signal into the main signal path such that the filtered analog signal is subtracted from a second signal derived from the analog input signal to provide the conditioned analog signal.

Analog signal conditioning

In accordance with embodiments of the present disclosure, a processing system may include multiple selectable processing paths for processing an analog signal in order to reduce noise and increase dynamic range. Techniques are employed to transition between processing paths and calibrate operational parameters of the two paths in order to reduce or eliminate artifacts caused by switching between processing paths.

Multi-path analog front end and analog-to-digital converter for a signal processing system

In accordance with embodiments of the present disclosure, a processing system may include a plurality of processing paths and a controller. The plurality of processing paths may include a static processing path configured to generate a first digital signal based on an analog input signal and a dynamic processing path configured to generate a second digital signal based on the analog input signal, wherein a parameter of the dynamic processing path is determined based on a characteristic of the analog input signal. The controller may be configured to select the first digital signal as a digital output signal of the processing system when a change is occurring to the characteristic and select the second digital signal as the digital output signal in the absence of change occurring to the characteristic.

Multi-path analog front end with adaptive path

A system may include an input for receiving an input signal, an output for generating an output signal, a capacitor coupled between the input and the output, a variable resistor coupled to the output and having a plurality of modes including a first mode in which the variable resistor has a first resistance and a second mode in which the variable resistor has a second resistance, and control circuitry configured to determine a difference between the input signal and the output signal and switch between modes of the plurality of modes when the difference is less than a predetermined threshold.

A system may comprise a high-pass filter having an input for receiving an input signal, an output for generating an output signal, a capacitor coupled between the input and the output, a switched-capacitor resistor coupled between the output and a reference voltage, and control circuitry configured to control the reference voltage to cancel current leakage into a circuit coupled to the output. The input, the output, the capacitor, and the switched-capacitor resistor may be arranged to generate the output signal as a high-pass filtered version of the input signal and the high-pass filter may be configured to operate in a plurality of modes comprising at least a high-impedance mode and a low-impedance mode in which the resistance of the switched-capacitor resistor is significantly smaller than the resistance when in the high-impedance mode.

A portable audio device may be configured to measure load characteristics of headphones. The device may measure direct current (DC) and/or alternating current (AC) characteristics of the load. These characteristics may be measured by an audio component, such as an audio codec chip or integrated circuit (IC) controller, and reported to software or firmware executing on a processor coupled to the audio component. The software or firmware may then take action based on the measured load characteristics. For example, the load characteristics may be compared to a database of headphones and their known load characteristics to determine a particular headphone model or type of headphone attached to the audio output. The processor may then apply an appropriate equalization curve.

Direct current (DC) and/or alternating current (AC) load detection for audio codec

In accordance with embodiments of the present disclosure, a processing system may include multiple selectable processing paths for processing an analog signal in order to reduce noise, increase dynamic range, and mask audio artifacts associated with a change in noise floor. Techniques are employed to transition between processing paths and calibrate operational parameters of the two paths in order to reduce or eliminate artifacts caused by switching between processing paths.

Systems and methods for reducing artifacts and improving performance of a multi-path analog-to-digital converter

A processing path may include a controller and a plurality of processing paths including a first processing path and a second processing path. The first path may be configured to generate a first digital signal based on an analog input signal and the second path may be configured to generate a second digital signal based on the analog input signal, wherein the first path has a lower gain and a higher noise floor than the second path. The controller may be configured to determine that a transition between the first path and the second path needs to occur based on the analog input signal crossing a threshold or a prediction that the input signal will cross the threshold and in response to determining the transition between the first path and the second path needs to occur, blend the transition during or near zero cross points of the analog input signal.

Systems and methods for reducing audio artifacts from switching between paths of a multi-path signal processing system

An audio playback path of an audio apparatus includes a digital modulator, a digital-to-analog converter (DAC), and a power amplifier. The digital modulator receives a playback signal corresponding to playback audio content and generates a digital input signal in accordance with the playback signal. The DAC receives the audio input signal and generates an analog preamplifier signal. The power amplifier generates an audio output signal in accordance with the preamplifier signal and an analog attenuation determined by the analog attenuation signal. The apparatus may include a volume control input to receive a volume control signal and a playback controller configured to perform operations including generating an analog attenuation signal in accordance with the volume control signal, monitoring a playback state indicated by the playback parameters, and responsive to detecting the playback state satisfying the playback criterion, modifying a selected playback parameter to improve a performance parameter of the playback path.

Opportunistic playback state changes for audio devices

An electronic device may be configured to identify a load coupled to the device. The device may measure direct current (DC) and/or alternating current (AC) characteristics of the load to identify the load. The device may then take action based on the identification of the load. For example, a specific transducer may be identified as coupled to the electronic device and an appropriate equalization curve applied to an audio output of the device. The measurement of characteristics of the load may include controlling a reference generator according to a search algorithm, such as a step ramp or binary search, to identify the load. An analog-to-digital converter (ADC) may operate through the search algorithm to provide feedback to digital circuitry regarding how to proceed through the search algorithm to identify the load.

Identification of a load with a search algorithm that controls application of signals to the load and a reference generator

A method may include processing an analog input signal with a first processing path configured to generate a first digital signal based on the analog input signal; processing the analog input signal with a second processing path configured to generate a second digital signal based on the analog input signal, and adapting a response of an adaptive filter configured to generate a filtered digital signal from the second digital signal to reduce a difference between the filtered digital signal and the first digital signal. The method may additionally or alternatively include determining nonlinearities present in the second processing path based on comparison of the first digital signal and the second digital signal, and applying a linear correction to the second digital signal to generate a corrected second digital signal with decreased nonlinearity from that of the second digital signal.

Matching paths in a multiple path analog-to-digital converter

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Austin, TX, United States of America

Daniel John Allen