Cirrus Logic Inc.

Cirrus Logic International Semiconductor Limited

Aaron J Brennan

John L Melanson

Ramin Zanbaghi

Yousof Mortazavi

Eric Jerome King

Christian Larsen

Daniel John Allen

Johann Guy Gaboriau

Lingli Zhang

Aniruddha Satoskar

Vamsikrishna Parupalli

Prashanth Drakshapalli

Firas Azrai

Yongjie Cheng

Dan Shen

Bharath Kumar Thandri

Roy Scott Kaller

Justin Dougherty

Mikel Ash

Thuan Luong Nguyen

Ramya Balasundaram

Adrian Colli-Menchi

An integrated circuit may have two signal paths: an open-loop modulator (which may comprise a digital-input Class-D amplifier) and a closed-loop modulator (which may comprise an analog-input Class-D amplifier). A control subsystem may be capable of selecting either of the open-loop modulator or the closed-loop modulator as a selected path based on one or more characteristics (e.g., signal magnitude) of an input audio signal. For example, for higher-magnitude signals, the closed-loop modulator may be selected while the open-loop modulator may be selected for lower-magnitude signals. In some instances, when the open-loop modulator is selected as the selected path, the closed-loop modulator may power off, which may reduce power consumption. In addition, one or more techniques may be applied to reduce or eliminate user-perceptible audio artifacts caused by switching between the open-loop modulator and the closed-loop modulator, and vice versa.

Systems and methods for dynamic range enhancement using an open-loop modulator in parallel with a closed-loop modulator

A system may include a charge pump configured to operate in a plurality of modes including a first mode in which the ratio of an output voltage to an input voltage of the charge pump is a first ratio and a second mode in which the ratio is a second ratio and a controller configured to limit current flowing between a power source of the charge pump to the charge pump, wherein the power source provides the input voltage, by limiting a transfer of charge between the power source and the charge pump during a switching cycle of the charge pump responsive to a change in operation between modes of the plurality of modes.

Charge pump input current limiter

In accordance with embodiments of the present disclosure, a system may include a series combination of a boost converter and a power converter coupled together in series, such that the series combination boosts an input voltage to the series combination to an output voltage greater than the input voltage such that a voltage boost provided by the series combination is greater than a voltage boost provided by the boost converter alone. The system may also include an amplifier, wherein an input of the amplifier is coupled to an output of the series combination of the boost converter and the power converter.

Combined boost converter and power converter

A method of increasing a multiplication ratio of a charge pump, the multiplication ratio defining a relationship between an output voltage of the charge pump and an input voltage of the charge pump, comprising: analyzing a first efficiency of the charge pump when the multiplication ratio is at a first ratio, calculating a second efficiency of the charge pump when the multiplication ratio is a second ratio lesser than the first ratio, and based on the first efficiency and the second efficiency, determining at least one of a target output power and a target output voltage at which to change the multiplication ratio from the second ratio to the first ratio.

Variable ratio charge pump with peak current and average current limiting circuitry

In accordance with embodiments of the present disclosure, a transconductance with capacitances feedback compensation amplifier may include a capacitor in parallel with an inner feedback loop of the amplifier for providing cascade compensation to the amplifier.

Transconductance with capacitances feedback compensation amplifier

The dynamic range and power efficiency of a voice-activated system may be improved by dynamically adjusting the configuration of the voice-activated system's input path. In one embodiment, a first portion of audio may be received through an input path of the voice-activated system having a first configuration. A characteristic of the first portion of audio may be determined and the input path may be adjusted to a second configuration based on the determined characteristic. A second portion of audio may then be received through the input path having the second configuration, and speech analysis may be performed on the second portion of audio.

Analog-to-digital converter (ADC) dynamic range enhancement for voice-activated systems

An analog-to-digital converter (ADC) may include capability to sense and/or compensate for undesired effects when receiving input from a microphone. For example, a sense node may be provided between differential inputs, and that sense node separated from the differential inputs by two or more switches. The sense node may allow for a measurement of an average voltage of the differential inputs. The average voltage may be obtained activating the switches to sample the sampling capacitors coupled to the differential inputs. That average voltage may be used as common mode (CM) data. A controller may receive the CM data, along with differential mode (DM) data, and use the CM and DM data to determine undesired effects, such as DC or AC mismatch at the microphone interface. The controller may then generate a signal for applying compensation to the differential inputs to reduce or eliminate the undesired effects.

Phase shorting switch

One method of processing microphone input in an ADC to determine microphone configuration is to process the microphone input signals in two processing paths, in which one processing path processes a difference between differential input signals and another processing path processes an average value of the differential input signals. The outputs of these processing paths may be combined to generate a digital signal representative of the analog signal from the microphone. The digital signal contains a digital version of the audio in the environment around the microphone, but may also be used to detect microphone topology and configure aspects of the processing paths to match the detected microphone topology. An apparatus for an ADC may implement the two processing paths as two delta-sigma modulator loops.

Dual processing paths for differential mode and common mode signals for an adaptable analog-to-digital converter (ADC) topology

The overall performance of a dual-path ADC system may be improved by using a VCO-based ADC for small-amplitude signals and employing non-linear cancelation to remove nonlinearities in signals output by the VCO-based ADC. In particular, VCO-based dual-path ADC systems of this disclosure may be configured to receive a first digital signal from a first ADC and a second digital signal from a second ADC, wherein the second digital signal is more non-linear than the first digital signal. The dual-path systems may also be configured to determine one or more non-linear coefficients of the second digital signal based, at least in part, on processing of the first and second digital signals. The dual-path systems may be further configured to modify the second digital signal based, at least in part, on the determined one or more non-linear coefficients to generate a more linear second digital signal.

Non-linearity cancellation in a dual-path ADC

In accordance with embodiments of the present disclosure, a method for identifying a location of an integrated circuit that is sensitive to RTS noise may include applying localized heat to a scan area of the integrated circuit, observing any change in one or more electrical parameters of the integrated circuit in response to the localized heat being applied to the scan area indicative of sensitivity to RTS noise, and identifying the location sensitive to RTS noise responsive to observing change in one or more electrical parameters of the integrated circuit indicative of sensitivity to RTS noise in response to the localized heat being applied to the scan area.

Random telegraph signal identification and measurement

An optical sensor may be integrated into headphones and feedback from the sensor used to adjust an audio output from the headphones. For example, an emergency vehicle traffic preemption signal may be detected by the optical sensor. Optical signals may be processed in a pattern discriminator, which may be integrated with an audio controller integrated circuit (IC). When the signal is detected, the playback of music through the headphones may be muted and/or a noise cancellation function turned off. The optical sensor may be integrated in a music player, a smart phone, a tablet, a cord-mounted module, or the earpieces of the headphones.

Headphone responsive to optical signaling

A circuit for a divider or counter may include a frequency divider having multiple rings for dividing an input frequency to obtain an output frequency. The first and second rings may include an odd-numbered plurality of elements, such as inverters, wherein each inverter of a ring is coupled to another inverter of the ring in a circular chain. An input frequency may be input to a power supply input of inverters of the first ring. The second ring inverters may be coupled at a power supply input to output nodes of the first ring inverters, which results in the second ring operating at a divisional rate of the first frequency given by (N&#x2212;1), where N is the number of inverters in the ring. The circuits may be used in frequency dividers and counters, such as in phase-locked loops (PLLs) and analog-to-digital converters (ADCs).

Ring frequency divider

The overall performance of a dual-path ADC system may be improved by using a VCO-based ADC for small-amplitude signals and employing non-linear cancellation to remove nonlinearities in signals output by the VCO-based ADC. In particular, VCO-based dual-path ADC systems of this disclosure may be configured to receive a first digital signal from a first ADC and a second digital signal from a second ADC, wherein the second digital signal is more non-linear than the first digital signal. The dual-path systems may also be configured to determine one or more non-linear coefficients of the second digital signal based, at least in part, on processing of the first and second digital signals. The dual-path systems may be further configured to modify the second digital signal based, at least in part, on the determined one or more non-linear coefficients to generate a more linear second digital signal.

A delta-sigma modulation analog-to-digital converter (ADC) may be constructed by combining a VCO used for a first order filter with a digital loop filter used for a second or higher order of the ADC. One such ADC would include an analog input node configured to receive an analog signal; a voltage-controlled oscillator (VCO) comprising a first input configured to receive the analog signal, wherein the voltage-controlled oscillator is configured to implement a first order noise-shaping function; a digital loop filter comprising a second input configured to receive an output of the voltage-controlled oscillator (VCO); and a digital output node configured to output a digital signal based on an output of the digital loop filter. The digital loop filter may be configured to implement at least a first order noise-shaping function, but may also implement higher order noise-shaping functions.

Voltage-controlled oscillator (VCO) as first stage in an analog-to-digital converter (ADC) in combination with a digital filter for second or higher-order noise shaping

Kickback current from a charge pump to a power management integrated circuit (PMIC) may be reduced by dissipating charge from fly and hold capacitors during mode transitions. A switch may be placed in series between the charge pump and the PMIC to disconnect the charge pump and prevent kickback current from reaching the PMIC. Further, additional loads, as switches, may be coupled to the charge pump outputs to dissipate charge from the fly and hold capacitors. Additionally, a closed feedback loop may be used to monitor and discharge excess charge from the fly and hold capacitors during mode transitions. Furthermore, charge may be redistributed between the fly and hold capacitors during mode transitions to reduce the time period of the transition.

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Austin, TX, United States of America

Aaron J Brennan