Abstract: A system may include an input configured to receive an audio signal, a filter having a negative group delay within a range of frequencies which are human-audible, the filter configured to receive the audio signal and filter the audio signal to generate a filtered audio signal, and a modulator configured to receive the filtered audio signal and modulate the filtered audio signal to generate a modulated filtered audio signal for communication over a digital interface.

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 boost converter may include a first stage comprising a first dual anti-wound inductor constructed such that its windings generate opposing magnetic fields in its magnetic core, and a second stage comprising a second dual anti-wound inductor constructed such that its windings generate opposing magnetic fields in its magnetic core. The boost converter may also include control circuitry for controlling the first stage and the second stage to have a plurality of phases comprising a first phase wherein a first coil of the first dual anti-wound inductor and a second coil of the second dual anti-wound inductor are coupled in parallel between a power supply and a ground voltage and a second phase wherein the first coil of the first dual anti-wound inductor and the second coil of the second dual anti-wound inductor are coupled in series between the power supply and the ground voltage.

Abstract: A system may include a modulator configured to generate a modulated data stream of samples from an input signal wherein each value of data in the modulated data stream when encoded is represented by a multi-bit code, wherein the modulator comprises a quantizer configured to quantize the modulated data stream from the input signal and feed back the modulated data stream as a feedback signal to an input of the modulator and a memory configured to store one or more samples of the modulated data stream. The system may also include an encoder configured to generate a synchronized serialized code stream from the modulated data stream. The quantizer may be configured to, based on the one or more samples of the modulated data stream stored in the memory, constrain the modulated data stream such that a synchronization state of the synchronized serialized code stream generated by the encoder is determinable based on the synchronized serialized code stream.

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 system may include an input configured to receive a digital audio input signal having at least four and fewer than 65,000 quantization levels and sampled at at least 500 kilohertz, a low-pass filter configured to receive the digital audio input signal and perform filtering on the digital audio input signal to generate a filtered digital audio input signal having a bandwidth of between approximately 100 hertz and 10 kilohertz, 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, wherein a group delay from the input to an output of the driver is less than 50 microseconds.

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: A system may include an input configured to receive an audio signal, a filter having a negative group delay within a range of frequencies which are human-audible, the filter configured to receive the audio signal and filter the audio signal to generate a filtered audio signal, and a modulator configured to receive the filtered audio signal and modulate the filtered audio signal to generate a modulated filtered audio signal for communication over a digital interface.

Abstract: A system may include a digital delta-sigma modulator configured to receive a digital audio input signal and quantize the digital audio input signal into a quantized signal, a filter configured to receive the quantized signal and perform filtering on the quantized signal to generate a filtered quantized signal, the filter having a variable group delay, and a current-mode digital-to-analog converter configured to receive the filtered quantized signal and convert the filtered quantized signal into an equivalent current-mode analog audio signal.

Abstract: 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.

Abstract: A method may include determining whether an electronic device having a haptic transducer is in an undesired noise-generating position and responsive to the electronic device being in the undesired noise-generating position, modifying playback of a haptic effect at the haptic transducer.

Abstract: An apparatus may include a power converter having a power supply input for receiving an input power supply voltage generated by a power supply, an output for generating an output voltage to a load, and a power inductor coupled between the power supply input and the output may and further include an energy storage element coupled to the power supply input, the power inductor, and the output such that operation of the power inductor is split temporally between delivering energy to the energy storage element and delivering energy to the load, and operation of the energy storage element is split temporally between delivering energy to the load and receiving energy from one or both of the power supply and the load.

Abstract: An apparatus performs interpolation/decimation in a digital circuit that receives an input signal and includes upsampling/downsampling and filtering stages. First and second paths include distinct first and second portions of the upsampling/downsampling and filtering stages. The first path consumes less quiescent state power. A selection circuit uses the first or second path and turns off the unused first or second path based on input signal spectral content or level. A mode includes applying a front-end digital/analog gain and a corresponding back-end analog/digital attenuation in conjunction with the first path being used and the second path being turned off. A cross-fader uses the first and second paths in a weighted mix manner while making a transition between using the first and second paths. The second path has higher filtering performance (e.g., superior stopband attenuation, passband ripple, transition band, e.g., via higher order or greater bit-width filtering).

Abstract: A 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 near-zero asymmetric quantizer configured to quantize the intermediate signal into a quantized output signal which is fed back as an input to the loop filter such that the quantized output signal has a plurality of quantization levels, wherein the plurality of quantization levels are asymmetric to zero.

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 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 temperature sensor having a two-state input current, an element whose temperature is sensed based on a change in voltage across the element induced by the two states of the input current, a charge-to-digital converter, and a capacitor continuously connected between the element and the charge-to-digital converter. The capacitor experiences a charge difference due to the change in voltage across the element induced by the two states of the input current, and the charge-to-digital converter converts the charge difference to a digital value indicative of the temperature of the element. A two-state DC-shifting current having opposite polarity of the two-state input current, a pull-down resistor whose voltage varies with the two-states of the DC-shifting current, and a second capacitor continuously connected between the pull-down resistor and the charge-to-digital converter operate to shift down a DC operating point of the charge-to-voltage converter to increase its dynamic range.

Abstract: In accordance with embodiments of the present disclosure, a system may include an impedance estimator configured to estimate an impedance of a load and generate a target current based at least on an input voltage and the impedance, a voltage feedback loop responsive to a difference between the input voltage and an output voltage of the load, and a current controller configured to, responsive to the voltage feedback loop, the impedance estimator, and the input voltage, generate an output current to the load.

Abstract: A system for estimating parameters of an electromagnetic load may include an input for receiving an input excitation signal to the electromagnetic load, a broadband content estimator that identifies at least one portion of the input excitation signal having broadband content, and a parameter estimator that uses the at least one portion of the input excitation signal to estimate and output one or more parameters of 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.