Abstract: A method for determining a direct current impedance of a transducer may include receiving an input signal indicative of an electrical power consumed by the transducer and calculating, by a thermal model of the transducer, the direct current impedance based on the electrical power.

Abstract: A system may include a charge pump configured to boost an input voltage of the charge pump to an output voltage greater than the input voltage, a current mode control loop for current mode control of a power amplifier powered by the output voltage of the charge pump, and a controller configured to, in a current-limiting mode of the controller, control an output power of the charge pump to ensure that an input current of the charge pump is maintained below a current limit, control the power amplifier by placing the power amplifier into a high-impedance mode during the current-limiting mode, and control state variables of a loop filter of the current mode control loop during the current-limiting mode.

Abstract: A system includes a sequencer that divides a reference waveform into reference sequences, a sequence adjuster, and a model that models non-linearities of a haptic rendering signal chain that includes a haptic transducer load and a driver to the load. For each reference sequence: the sequence adjuster transforms the reference sequence into a test sequence using one or more parameters (e.g., changes reference sequence amplitude and/or period), the model generates an output in response to the test sequence, an error signal is generated that measures a difference between the output and the reference sequence, and if the error signal is above a threshold the parameters are adjusted based on the error signal. These operations are repeated until the error signal is below the threshold in which case the test sequence becomes a selected sequence, which is then sent to the haptic rendering signal chain.

Abstract: A method for identifying a mechanical impedance of an electromagnetic load may include generating a waveform signal for driving an electromagnetic load, the waveform signal comprising a first tone at a first driving frequency and a second tone at a second driving frequency. The method may also include during driving of the electromagnetic load by the waveform signal or a signal derived therefrom, receiving a current signal representative of a current associated with the electromagnetic load and a back electromotive force signal representative of a back electromotive force associated with the electromagnetic load.

Abstract: A method for identifying a mechanical impedance of an electromagnetic load may include generating a waveform signal for driving an electromagnetic load and, during driving of the electromagnetic load by the waveform signal or a signal derived therefrom, receiving a current signal representative of a current associated with the electromagnetic load and a back electromotive force signal representative of a back electromotive force associated with the electromagnetic load. The method may also include implementing an adaptive filter to identify parameters of the mechanical impedance of the electromagnetic load, wherein an input of a coefficient control for adapting coefficients of the adaptive filter is a first signal derived from the back electromotive force signal and a target of the coefficient control for adapting coefficients of the adaptive filter is a second signal derived from the current signal.

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: 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: A system for performing force sensing with an electromagnetic load may include a signal generator configured to generate a signal for driving an electromagnetic load and a processing subsystem configured to monitor at least one operating parameter of the electromagnetic load and determine a force applied to the electromagnetic load based on a variation of the at least one operating parameter.

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 resonant frequency tracker for driving an electromagnetic load with a driving signal may include a signal generator configured to generate a waveform signal at a driving frequency for driving an electromagnetic load and control circuitry. The control circuitry may be configured to, during driving of the electromagnetic load by the waveform signal or a signal derived therefrom, receive a current signal representative of a current associated with the electromagnetic load and a second signal representative of a second quantity associated with the electromagnetic load, the second quantity comprising one of a voltage associated with the electromagnetic load or a back electromotive force of the electromagnetic load. The control circuitry may be further configured to calculate a phase difference between the current signal and the second signal, determine a frequency error of the waveform signal based on the phase difference, and control the driving frequency based on the frequency error.

Abstract: A method for identifying a mechanical impedance of an electromagnetic load may include generating a waveform signal for driving an electromagnetic load, the waveform signal comprising a first tone at a first driving frequency and a second tone at a second driving frequency. The method may also include during driving of the electromagnetic load by the waveform signal or a signal derived therefrom, receiving a current signal representative of a current associated with the electromagnetic load and a back electromotive force signal representative of a back electromotive force associated with the electromagnetic load.

Abstract: A class-D amplifier system includes one or more pulse width modulation (PWM) output paths at least one of which includes one or more digital closed-loop PWM modulators (DCL-PWMM) in which at least one of the DCL_PWMM includes a digital integrator that provides an output value and receives a feedback value. The output value has an output resolution and the feedback value has a feedback resolution that is coarser than the output resolution. The output value is the sum of an integer multiple of the feedback resolution and a residue. Control logic decreases/increases the residue of the digital integrator toward an integer multiple of the feedback resolution over a plurality of clock cycles in response to a request to transition the class-D amplifier and forces an output of the DCL_PWMM to have an approximate 50% duty cycle after decreasing/increasing the residue over the plurality of clock cycles.

Abstract: A system may include a resistive-inductive-capacitive sensor, a driver configured to drive the resistive-inductive-capacitive sensor at a driving frequency, and a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor and 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, wherein the displacement of the mechanical member causes a change in an impedance of the resistive-inductive-capacitive sensor.

Abstract: A method of determining a phase misalignment between a first signal generated from a first signal path and a second signal generated from a second signal path may include obtaining multiple samples of the first signal proximate to when the first signal crosses zero wherein the first signal can be approximated as linear; obtaining multiple samples of the second signal proximate to when the second signal crosses zero wherein the first signal can be approximated as linear; based on the multiple samples of the first signal, approximating a first time at which the first signal crosses zero; based on the multiple samples of the second signal, approximating a second time at which the second signal crosses zero; and determining the phase misalignment between the first signal and the second signal based on a difference between the first time and the second time.

Abstract: A method may include receiving an analog modulated signal generated from a baseband signal modulated with a carrier signal wherein the baseband signal is representative of a capacitance of a capacitive sensor, converting the analog modulated signal into an equivalent digital modulated signal, demodulating the digital modulated signal to generate a demodulated digital signal representative of the capacitance of the capacitor wherein the demodulating is based, at least in part, on the carrier signal, and converting the demodulated digital signal into a digital output signal representative of a displacement of a plate of the capacitive sensor or a rate of displacement of a plate of the capacitive sensor.

Abstract: In accordance with embodiments of the present disclosure, a system may have a configurable control loop technology, wherein the system comprises a first mode control loop, a second mode control loop and a reconfigurable pulse width modulator (PWM) configured to generate an output signal from an input signal. The reconfigurable PWM may include a digital PWM and an analog PWM and may be configured such that when the first mode control loop is activated, the reconfigurable PWM utilizes the analog PWM to generate the output signal from the input signal and when the second mode control loop is activated, the reconfigurable PWM utilizes the digital PWM to generate the output signal from the input signal and the digital PWM receives its input from a digital proportional integral derivative controller.

Abstract: A system may include a charge pump configured to boost an input voltage of the charge pump to an output voltage greater than the input voltage, a current mode control loop for current mode control of a power amplifier powered by the output voltage of the charge pump, and a controller configured to, in a current-limiting mode of the controller, control an output power of the charge pump to ensure that an input current of the charge pump is maintained below a current limit, control the power amplifier by placing the power amplifier into a high-impedance mode during the current-limiting mode, and control state variables of a loop filter of the current mode control loop during the current-limiting mode.

Abstract: In accordance with embodiments of the present disclosure, a system may have a configurable control loop technology, wherein the system comprises a first mode control loop, a second mode control loop and a reconfigurable pulse width modulator (PWM) configured to generate an output signal from an input signal. The reconfigurable PWM may include a digital PWM and an analog PWM and may be configured such that when the first mode control loop is activated, the reconfigurable PWM utilizes the analog PWM to generate the output signal from the input signal and when the second mode control loop is activated, the reconfigurable PWM utilizes the digital PWM to generate the output signal from the input signal and the digital PWM receives its input from a digital proportional integral derivative controller.

Abstract: A DC servo loop may track DC offset changes of an input signal and apply feedback to amplifiers to adjust a DC offset of the input signal. The DC servo loop may include digital loop tracking and analog loop tracking components. The digital loop tracking components may track small changes in the DC offset. When the DC offset exceeds a certain threshold, analog loop tracking may be activated to apply feedback to the amplifiers to adjust the DC offset. The adjustments to the DC offset may be delayed until an amplitude of the input signal exceeds a threshold to reduce contribution to noise in the input signal.

Abstract: A simplified digital implementation of a fourth order Linkwitz-Riley crossover network is provided using approximations and transformations of the classical form. The approximation is particularly beneficial when the crossover frequency is low relative to the digital sampling rate, such as when an audio stream is split between bass and treble at about 30-300 Hz and the sampling frequency is about 100 times the cutoff frequency or higher. Rather than merely cascading two sets of second order filters, such as Butterworth filters, a fourth order transfer function is more directly implemented. Conventional transfer functions are simplified through approximations resulting in the elimination of all except one parameter, c, which is a linear function of the cutoff frequency. Additionally, multipliers are moved in line with the integrator elements.