Abstract: This application relates to voltage regulators and, particular, to low-dropout regulators (LDOs). The regulator (300) has an output stage (102) which receives an input voltage (Vin) and outputs an output voltage (Vout) and which includes at least one transistor (103) as an output device configured to pass an output current to the output, based on a drive voltage (V1). A differential amplifier (101) is configured to receive a feedback signal derived from the output voltage and also a reference voltage (REF) to generate an amplifier output to control the drive voltage (V1) to minimise any difference between the feedback signal and the reference voltage. A controller (301) is operable to selectively reconfigure the output stage to provide a change in output current in response to a load activity signal (ACT), which is indicative of a change in load activity that results in a change in load current demand for a load connected, in use, to the output.

Abstract: A method of management of a battery that powers a component of a device may include monitoring a terminal voltage and a terminal current of the battery under a load that is drawing a current on the battery to provide power to a component of the device and modeling the battery as a battery model that approximates a relationship between the monitored terminal voltage and terminal current over at least one of: a certain frequency range; a certain duration, a certain amplitude range, an applied load, a set of conditions of the battery, and a set of conditions of the load. The relationship between the terminal voltage and the terminal current may have a frequency-dependent characteristic including at least two time constants. The two time constants may represent a time-varying relationship between an input and output of the battery model.

Abstract: Driver circuitry for driving a load based on an input signal, comprising: at least one variable boost stage comprising: first and second input nodes configured to receive a first voltage and a second voltage respectively; first and second flying capacitor nodes for connection to a flying capacitor therebetween; a network of switching paths for selectively connecting the first and second input nodes with the first and second flying capacitor nodes; an output stage for selectively connecting a driver output node to each of the first and second flying capacitor nodes; and a controller operable in a first boost mode to: control the output stage to selectively connect the driver output node to the first flying capacitor node; control the network of switching paths to switch connection of the second flying capacitor node between the first and second input nodes at a controlled duty cycle; and in a first charge top-up cycle, control the network of switching paths to connect the first input node to the first flying c

Abstract: A high CMRR current monitoring circuit includes a first stage that receives a current sense signal, a voltage across a current sense resistor in series with an output of a class-D amplifier. First stage is powered by at least one floating supply and/or reference that tracks the amplifier output. First stage applies gain to the current sense signal to generate an intermediate signal. A second stage receives the intermediate signal and is powered by a ground-referenced supply and provides an amplified representation of the current sense signal. The floating supply is supplied by a capacitive-coupled power source driven by the ground-referenced supply. The second stage output may be a voltage relative to ground or a digital signal. The intermediate signal may be a current, digital signal, or amplified version of the current sense signal voltage. The first stage may be a transconductance amplifier and the second stage a transimpedance amplifier.

Abstract: A PWM modulator has a quantizer that generates a PWM output signal to speaker driver. When a first voltage swing range is supplied to the speaker driver, the quantizer analog gain is controlled to be a first gain value. When a second PWM drive voltage swing range is supplied to the speaker driver, the analog gain is controlled to be a second gain value. The first and second gain values of the analog gain of the quantizer cause the combined gain of the quantizer and driver to be approximately equal in the two modes. The quantizer has at least two gain-affecting measurable non-ideal characteristics. The quantizer is adjustable using measured first and second values to correct for first and second of the at least two non-ideal characteristics. The gain of the quantizer is calibratable while the quantizer is adjusted using the measured first and second measured values.

Abstract: A data acquisition system (DAS) for processing an input signal from a resistive sensor (e.g., Hall effect sensor) includes a sensor signal path that digitizes the input signal. An input impedance of the sensor signal path attenuates the input signal. A gain error corrector applies a gain error correction factor in a digital domain of the DAS to the digitized input signal to compensate for a loading effect to the resistive sensor. The sensor signal path includes an inverting amplifier that provides low distortion for the input signal and an ADC (e.g., delta-sigma, SAR, pipelined, auxiliary) that digitizes the input signal. A sensor characterization path digitizes the sensor resistance which the gain error corrector uses, along with the inverting amplifier input impedance, to calculate the gain error correction factor.

Abstract: A system may include a signal generator configured to generate a raw waveform signal and a modeling subsystem configured to implement a discrete time model of an electromagnetic load that emulates a virtual electromagnetic load and further configured to modify the raw waveform signal to generate a waveform signal for driving the electromagnetic load by modifying the virtual electromagnetic load to have a desired characteristic, applying the discrete time model to the raw waveform signal to generate the waveform signal for driving the electromagnetic load, and applying the waveform signal to the electromagnetic load.

Abstract: Driver circuitry for driving an electromechanical load with a drive output signal based on a digital reference signal at a first sample rate, the drive output signal inducing a first electrical quantity at the electromechanical load, the driver circuitry comprising: a function block configured, based on said first electrical quantity, to digitally determine at a second sample rate higher than the first sample rate an adjustment signal indicative of a second electrical quantity which would be induced at a target output impedance of the driver circuitry due to said first electrical quantity; and a driver configured to generate the drive output signal based on the reference signal and the adjustment signal to cause the drive output signal to behave as if an output impedance of the driver circuitry has been adjusted to comprise the target output impedance, wherein the first electrical quantity is a current and the second electrical quantity is a voltage, or vice versa.

Abstract: A dynamically stabilizable amplifier drives an output current into an RLC load. A driver stage generates the output current, and a control circuit compares a current level of the amplifier output with a threshold and selectively enables a stabilizing resistor (to selectively shunt the load or dampen in series with the load, depending on RLC load type) at the driver stage output based on the comparison so that the amplifier is stable across a range of the output current level. The control circuit disables the resistor when the output current is above the highest threshold and enables it when below. The control circuit may control the resistor to have one of multiple resistance values based on a comparison with multiple thresholds. The output current level may be determined by replicating the output current level or by an input current level that sets the output current level independent of the load.

Abstract: This application relates to methods and apparatus for driving a transducer with switching drivers. A switching driver has first and second supply node for receiving supply voltages and includes an output bridge stage, a capacitor and a network of switches. The network of switches is operable in different switch states to provide different switching voltages to the output bridge stage. A controller is configured to control the switch state of the network of switches and a duty cycle of output switches of the output bridge stage based on an input signal to generate an output signal for driving the transducer.

Abstract: 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.

Abstract: A method and apparatus for detecting a microphone condition of a microphone, the method comprising: applying an electrical stimulus to a microphone; measuring an electrical response to the electrical stimulus at the microphone; comparing the electrical response to an expected response; and determining the microphone condition based on the comparison.

Abstract: A system may include a power converter comprising at least one stage having a dual anti-wound inductor having a first winding and a second winding constructed such that its windings generate opposing magnetic fields in its magnetic core and constructed such that a coupling coefficient between the first winding and the second winding is less than approximately 0.95 and a current control subsystem for controlling an electrical current through the dual anti-wound inductor, the current control subsystem configured to minimize a magnitude of a magnetizing electrical current of the dual anti-wound inductor to prevent core saturation of the dual anti-wound inductor and regulate an amount of output electrical current delivered by the power converter to the load in accordance with a reference input signal.

Abstract: A system may include a sensor having a variable phase response, a dummy impedance having a known phase response, and a measurement circuit communicatively coupled to the sensor and configured to measure first phase information associated with the sensor, measure second phase information associated with the dummy impedance, and determine a phase response of the measurement circuit based on a comparison of the first phase information to the second phase information.

Abstract: Embodiments described herein provide an audio device and a method of operating the audio device. The audio device comprises at least one surface, a first surface transducer positioned to excite first modes of oscillation in a first surface of the at least one surface, and a second surface transducer positioned to excite second modes of oscillation in a second surface of the at least one surface, wherein the first modes of oscillation are of a higher frequency than the second modes of oscillation.

Abstract: This application relates to methods and apparatus for driving a transducer with switching drivers. A switching driver has first and second supply node for receiving supply voltages and includes an output bridge stage, a capacitor and a network of switches. The network of switches is operable in different switch states to provide different switching voltages to the output bridge stage. A controller is configured to control the switch state of the network of switches and a duty cycle of output switches of the output bridge stage based on an input signal to generate an output signal for driving the transducer.

Abstract: This application relates to methods and apparatus for driving a transducer with switching drivers where the switching driver has an output bridge stage for switching an output node between switching voltages and a modulator for controlling the duty cycle of the output bridge stage based on an input signal. The switching driver also includes a voltage controller for providing the switching voltages which is operable to provide different switching voltages in different driver modes. A controller is provided to control the driver mode of operation and the duty cycle of the switching driver based on the input signal, and the controller is configured to transition from a present driver mode to a new driver mode by controlling the voltage controller to provide the switching voltages for the new mode and controlling the modulator to vary the duty cycle of the output bridge stage. The change in duty cycle is controlled such that there is no substantial discontinuity in switching ripple due to the mode transition.

Abstract: This application relates to methods and apparatus for driving a transducer with switching drivers. A driver circuit has first and second switching drivers for driving the transducer in a bridge-tied-load configuration, each of the switching drivers having a respective output stage for controllably switching the respective driver output node between high and low switching voltages with a controlled duty cycle. Each of switching drivers is operable in a plurality of different driver modes, wherein the switching voltages are different in said different driver modes. A controller controls the driver mode of operation and the duty cycle of the switching drivers based on the input signal. The controller is configured to control the duty cycles of the first and second switching drivers within defined minimum and maximum limits of duty cycles; and to transition between driver modes of operation when the duty cycle of one of the switching drivers reaches a duty cycle limit.

Abstract: A data acquisition system (DAS) for acquiring data from a Hall effect sensor includes one or more state variables, a multiplexer that periodically rotates a signal from the Hall effect sensor, and a controller that resets the one or more state variables in synchronization with rotation of the signal. The state variables may be digital states in a digital memory or voltages of capacitors the controller forces to a reset voltage. The state variables may be included in a noise-shaping SAR ADC, a delta-sigma ADC, a digital filter, an integrator, an analog filter, a VCO, an incremental ADC or an auxiliary ADC-assisted incremental ADC, or an auxiliary ADC of the DAS.

Abstract: A data acquisition system (DAS) for processing an input signal from a resistive sensor (e.g., Hall effect sensor) includes a sensor signal path that digitizes the input signal. An input impedance of the sensor signal path attenuates the input signal. A gain error corrector applies a gain error correction factor in a digital domain of the DAS to the digitized input signal to compensate for a loading effect to the resistive sensor. The sensor signal path includes an inverting amplifier that provides low distortion for the input signal and an ADC (e.g., delta-sigma, SAR, pipelined, auxiliary) that digitizes the input signal. A sensor characterization path digitizes the sensor resistance which the gain error corrector uses, along with the inverting amplifier input impedance, to calculate the gain error correction factor.