Cirrus Logic Inc.

Vamsikrishna Parupalli

Eric B Smith

John L Melanson

Zhong You

Nishant Jain

Johann Guy Gaboriau

Saurabh Singh

Mengde Wang

Lei Zhu

Ku He

Amar Vellanki

Mark May

Graeme Gordon Mackay

Itisha Tyagi

Stewart G Kenly

Vikrant Arumugam

Gaurav Agarwal

Ramin Zanbaghi

Christian Larsen

Lingli Zhang

Marc Laurent Tarabbia

Graeme G Mackay

Prashanth Drakshapalli

Aaron J Brennan

Melvin L Hagge

Mikel Ash

Jianping Wen

Ramya Balasundaram

Akhilesh Persha

Katy Holland

Jeremy Babcock

A system may include a pulse-width modulation mode path configured to drive a load at an output of the system in a first mode of operation, a linear mode path configured to drive the load in a second mode of operation, a common mode control feedback loop configured to set a value of a common mode output signal at the output in the second mode of operation, and an auxiliary circuit coupled to the common mode feedback control loop and configured to maintain a state of the common mode feedback control loop during the first mode of operation as the state was or will be during the second mode of operation.

Output common-mode control loop for fast and smooth transition in multi-mode amplifiers

Techniques for reducing electromagnetic interference (EMI) in a switching amplifier circuit, control edge-rate with reduced sensitivity to process and temperature variations and that is reduced with increasing power supply voltage. The techniques control current levels in a pre-driver stage that drives an output driver of a switching amplifier circuit, according to a bias control. A first slope of a variation of the bias control with respect to a power supply voltage of the switching amplifier circuit over a first portion of a range of variation of the power supply voltage has a direction opposite a second slope of the variation of the reference output current with respect to the power supply voltage over a second portion of the range of variation of the power supply voltage. The resulting operation reduces electromagnetic interference generated by the driver over the second portion of the range of variation of the power supply voltage.

Parametric-insensitive edge rate control in switched-power circuits with tailored power supply voltage sensitivity

A differential amplifier provides improved signal swing and reduced common-mode output noise. The differential amplifier circuit includes a driver circuit with a first output for driving a first output of the differential amplifier and with a second output for driving a second output of the differential amplifier. The driver circuit has inputs for receiving a differential (complementary) pair of input signals at least one common-mode reference input for receiving a common-mode reference signal. The differential amplifier also includes a signal maxima detector having inputs for receiving the differential input signals that detects a maximum value between the individual signals, including any input common-mode voltage. The differential amplifier also includes a common-mode reference circuit that provides the common-mode reference signal and an input coupled to an output of the signal maxima detector, so that a common-mode voltage of the outputs is independent of power supply voltages provided to the driver circuit.

Differential driver having input signal-controlled common-mode reference

Accurate operation of a current monitor is provided by injecting a bias voltage to a maintain de-selected sense amplifier input in an active state. An electronic system includes an output stage to supply a load current and includes two push-pull output drivers having sense resistors supplying a first and a second sense voltage. An included mode control circuit selects between a first and a second operating mode and selects a polarity of the current. An included current monitor receives the sense voltages and has a control input coupled to the mode selection control circuit. The current monitor provides an output that is dependent on both sense voltages in the first operating mode and is indicative of one of the sense voltages selected according to the selected polarity in the second operating mode. The bias voltage is injected into an unselected sense inputs to maintain active operation of the sense amplifier.

Compensating current monitor for electronic systems having mode-sensitive selection of current-sensing inputs

A SAR ADC may include a plurality of capacitor networks, wherein each capacitor network of a plurality of capacitor networks has a plurality of sampling capacitors for sampling over a plurality of sampling sub-phases an analog input signal to the SAR ADC and at least one non-sampling capacitor. The SAR ADC may also include a DAC comprising a plurality of sub-DACs including at least a first sub-DAC representing most significant bits of an output of the SAR ADC, wherein the output of the first sub-DAC is coupled to the sampling capacitors of the plurality of capacitor networks and a second sub-DAC representing bits of the output of the SAR ADC lesser in magnitude significance than those of the first sub-DAC, wherein the output of the second sub-DAC is coupled to a respective one of at least one non-sampling capacitor of each of the plurality of capacitor networks.

Successive approximation register analog-to-digital converter with multiple sample capacitors

An integrated circuit (IC) provides on-line, wafer-level, die-level, or package-level thermal calibration of an integrated thin-film resistor, by thermally enclosing the thin-film resistor with metal layers formed above and below the thin-film resistor along its length and width. Metal vias thermally couple the metal layers to the substrate to at least partially equalize the temperature of the metal layers and the thin-film resistor and the substrate. A controllable heat source, which may be provided by another thin-film resistor integrated on or below the substrate, and a reference temperature sensor provide heating/calibration measurement of the resistance of the thin-film resistor over a range of temperature. The reference temperature sensor may be provided within the IC, for example, integrated on the substrate or packaged with the die containing the thin-film resistor, or may be otherwise thermally coupled to the metal layers, e.g., by an extension of one of the metal layers.

Integrated thin-film resistive sensor with integrated heater and metal layer thermal equalizer

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 senses motor current and provides outputs to the pulse-width modulator and the linear amplifier stage.

Cross-over distortionless pulse-width modulated (PWM)/linear motor control system

An electronic control system provides selectable linear and pulse-width modulated (PWM) operation with reduced disruption when changing from PWM operation to linear operation. The system includes an output stage that has a push-pull driver coupled to the load, which may be a motor, a haptic device, or other device requiring current-mode control. The system also includes a pulse-width modulated (PWM) driver for providing pulse-width modulated drive signals to gates of the transistors of the output stage when a pulse-width modulated mode is selected, and a linear amplifier stage that provides a linear analog signal to the gates of the transistors when a linear mode is selected. A pre-charging circuit pre-charges the gates during a pre-charge cycle that is initiated when the operating mode changes from the PWM operating more to the linear operating mode.

Pre-biased mode switching in system having selectable pulse-width modulated (PWM) and linear operation

An electronic control system provides selectable path operation, such as linear and pulse-width modulated (PWM) operation and provides path transition management to improve operation. The system supplies a current or a voltage to a load in response to an input signal or value and includes an output driver, and multiple selectable control paths. The system includes a control circuit that selects between the first control path and the second control path in response to a path selection indication to drive the output driver. The system may include an evaluator that determines the path selection indication in conformity with an amplitude and a slew rate of the input. One or all of the control paths may have a response time to changes in the input signal or value, and the control circuit may delay switching from the second control path to the first control path to compensate for the response time.

Management of path selection in a multi-path control system

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.

Dynamic stability control in amplifier driving high Q load

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.

Capacitive sensor including compensation for phase shift

A system may include an output stage for driving a load at an output of the output stage, a pulse-width modulation mode path configured to pre-drive the output stage in a first mode of operation, a linear mode path configured to pre-drive the output stage in a second mode of operation and a loop filter coupled at its input to the output of the output stage and coupled at its output to both of the pulse-width modulation mode path and the linear mode path. The pulse-width modulation mode path and the linear mode path may be configured such that a first transfer function between the output of the loop filter and the output of the output stage is substantially equivalent to a second transfer function between the output of the loop filter and the output of the output stage.

Closed loop control in a camera module

A system may include an output stage comprising a single-ended driver for driving a load at an output of the output stage, a loop filter coupled at its input to the output of the output stage and configured to minimize an error between a target current signal received by the loop filter and an output current driven on the load, and control circuitry configured to, when the load current is driven in a manner such that the load current changes polarity, reset a state variable of the loop filter.

Minimizing crossover distortion in a class B current driver

A method for calculating a calibration gain used for common-mode rejection in a current sensing system may include measuring a first value of a common-mode voltage associated with the current sensing system and a first output value of the current sensing system occurring at the first value of the common-mode voltage, measuring a second value of the common-mode voltage associated with the current sensing system and a second output value of the current sensing system occurring at the second value of the common-mode voltage, and based on a difference between the second output value of the current sensing system and the first output value of the current sensing system and a difference between the second value of the common-mode voltage and the first value of the common-mode voltage, calculating the calibration gain.

Calibration of current sense amplifier with common-mode rejection

In accordance with embodiments of the present disclosure, a method for power supply rejection for an amplifier may include generating a correction signal by multiplying a quantity indicative of a power supply voltage of the amplifier by a transfer function defining a response from the power supply voltage of the amplifier to an output signal of the amplifier and subtracting the correction signal from a signal within a signal path of a circuit comprising the amplifier.

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Austin, TX, United States of America

Vamsikrishna Parupalli