Apparatus and method for measuring speaker transducer impedance versus frequency with ultralow inaudible signal

    公开(公告)号:US11070179B2

    公开(公告)日:2021-07-20

    申请号:US16562116

    申请日:2019-09-05

    Abstract: An apparatus measures a speaker impedance. A DAC converts a known digital input signal to an audio frequency first analog voltage signal. Resistors with known resistance attenuate the first analog voltage signal to generate a current. The known resistance effectively determines the current because the known resistance is high relative to the speaker impedance. The current is sourced into the speaker to generate a second analog voltage signal. The known resistance is sufficiently high to cause the second analog voltage signal to be inaudible as transduced by the speaker. An amplifier amplifies the second analog voltage signal with a known gain to generate a third analog voltage signal. An ADC converts the third analog voltage signal to a digital output signal. A processing element calculates the impedance of the speaker proportional to the digital output signal based on the known digital input signal, the known resistance, and the known gain.

    Capacitive sensor including compensation for phase shift

    公开(公告)号:US10649015B1

    公开(公告)日:2020-05-12

    申请号:US15943154

    申请日:2018-04-02

    Abstract: A method may include applying an excitation signal to a capacitor of the capacitive sensor which causes generation of a modulated signal from an input signal indicative of a variance in a capacitance of the capacitor, detecting the modulated signal with a detector to generate a detected modulated signal that has a phase shift relative to the excitation signal, demodulating the detected modulated signal into an in-phase component and a quadrature component using a reference signal, nullifying the quadrature component by setting a phase of the reference signal relative to the excitation signal to compensate for the phase shift, and outputting the in-phase component as an unmodulated output signal representative of the capacitance.

    Resonant tracking of an electromagnetic load

    公开(公告)号:US12035445B2

    公开(公告)日:2024-07-09

    申请号:US16556849

    申请日:2019-08-30

    CPC classification number: H05B6/04 G08B6/00 H02M7/48

    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.

    Compensation of changes in a resonant phase sensing system including a resistive-inductive-capacitive sensor

    公开(公告)号:US11092657B2

    公开(公告)日:2021-08-17

    申请号:US16354695

    申请日:2019-03-15

    Abstract: A system may include a resonant phase sensing system comprising a resistive-inductive-capacitive sensor and a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor, and a compensation circuit. The measurement circuit may be configured to use a phase detector to measure phase information associated with the resistive-inductive-capacitive sensor and based on the phase information, determine a displacement of a metal plate relative to the resistive-inductive-capacitive sensor. The compensation circuit may be configured to detect a change in a physical property associated with the resistive-inductive-capacitive sensor other than the displacement and compensate the phase information to correct for the change in the physical property.

    CROSS-OVER DISTORTIONLESS PULSE-WIDTH MODULATED (PWM)/LINEAR MOTOR CONTROL SYSTEM

    公开(公告)号:US20220337181A1

    公开(公告)日:2022-10-20

    申请号:US17230789

    申请日:2021-04-14

    Abstract: An electronic motor control system provides selectable linear and pulse-width modulated (PWM) operation without generating cross-over distortion. The system includes an output stage that has a pair of push-pull drivers each coupled to a terminal of the motor. The electronic motor control system also includes a pulse-width modulated (PWM) driver for providing pulse-width modulated drive signals to an input of the output stage when the pulse-width modulated mode is selected and a linear amplifier stage that provides a linear analog signal to the input of the output stage in linear mode, so that both drivers are operated to supply the current to the motor. In pulse-width modulated mode, a driver is selected for PWM operation, while the other driver is operated to supply a fixed voltage. A feedback control loop motor current and provides outputs to the pulse-width modulator the linear amplifier stage.

    Reducing noise in a capacitive sensor with a pulse density modulator

    公开(公告)号:US11035894B2

    公开(公告)日:2021-06-15

    申请号:US16890727

    申请日:2020-06-02

    Abstract: A method for measuring a capacitive sensor output may include applying an excitation signal to a capacitor of the capacitive sensor which causes generation of a modulated signal from a baseband signal, wherein the excitation signal is of a carrier frequency which is higher than frequency content of the baseband signal, demodulating the modulated signal to generate an intermediate signal representative of a capacitance of the capacitor wherein the demodulating is based, at least in part, on the excitation signal, converting the intermediate signal into a pulse-density modulated output signal with a pulse-density modulator, and shaping a noise transfer function of the pulse-density modulator to have an approximate zero at the carrier frequency.

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