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 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: 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: 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. 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. 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: 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: The disclosure provides a system, comprising: a MEMS capacitive transducer, comprising one or more first capacitive plates coupled to a first node and one or more second capacitive plates coupled to a second node; biasing circuitry coupled to the first node, operable to provide a biasing voltage to the one or more first capacitive plates; and test circuitry coupled to the second node, operable to: selectively apply one or more current sources to the second node, so as to charge and discharge the MEMS capacitive transducer and so vary a signal based on a voltage at said second node between an upper value and a lower value; determine a parameter that is indicative of a time period of the variation of the signal; and determine a capacitance of the MEMS capacitive transducer based on the parameter that is indicative of the time period.

Abstract: The application describes MEMS transducers having a patterned membrane electrode which incorporates a plurality of openings or voids. A conductive element is provided on the surface of the underlying membrane within the opening.

Abstract: The disclosure provides a system, comprising: a MEMS capacitive transducer, comprising one or more first capacitive plates coupled to a first node and one or more second capacitive plates coupled to a second node; biasing circuitry coupled to the first node, operable to provide a biasing voltage to the one or more first capacitive plates; and test circuitry coupled to the second node, operable to: selectively apply one or more current sources to the second node, so as to charge and discharge the MEMS capacitive transducer and so vary a signal based on a voltage at said second node between an upper value and a lower value; determine a parameter that is indicative of a time period of the variation of the signal; and determine a capacitance of the MEMS capacitive transducer based on the parameter that is indicative of the time period.

Abstract: The disclosure provides a system, comprising: a MEMS capacitive transducer, comprising one or more first capacitive plates coupled to a first node and one or more second capacitive plates coupled to a second node; biasing circuitry coupled to the first node, operable to provide a biasing voltage to the one or more first capacitive plates; and test circuitry coupled to the second node, operable to: selectively apply one or more current sources to the second node, so as to charge and discharge the MEMS capacitive transducer and so vary a signal based on a voltage at said second node between an upper value and a lower value; determine a parameter that is indicative of a time period of the variation of the signal; and determine a capacitance of the MEMS capacitive transducer based on the parameter that is indicative of the time period.

Abstract: A bias circuit for a capacitive sensor may include a variable impedance element coupled to a capacitor of the capacitive sensor wherein an impedance of the variable impedance element is varied in accordance with a temperature associated with the bias circuit and an active feedback circuit coupled between the variable impedance element and an output of a processing circuit for processing a signal generated by the capacitive sensor and configured to drive the variable impedance element to force a direct-current (DC) voltage level of an output of the capacitive sensor to a desired voltage.

Abstract: A variable resistor may be coupled between a reference voltage source and components of an integrated circuit to reduce issues relating to thermal noise from a reference voltage signal generated by the reference voltage source. The variable resistor may be set to a low level during a first time period and a high level during a second time period, in which the time periods correspond to a sampling period of a switched-capacitor circuit. The low resistance time period may allow quick settling of an input reference voltage signal, whereas the high resistance time period may reduce a bandwidth of noise on a sampling capacitor coupled to the reference voltage signal. The variable resistor and switched-capacitor network may be used in an analog-to-digital converter (ADC), such as in audio circuits.

Abstract: A MEMS microphone may include a backplate comprising first and second electrodes electrically isolated from one another and mechanically coupled to the backplate in a fixed relationship relative to the backplate and a diaphragm configured to displace relative to the backplate as a function of sound pressure incident upon the diaphragm, the diaphragm comprising third and fourth electrodes electrically isolated from one another and mechanically coupled to the diaphragm in a fixed relationship relative to the diaphragm such that the third and fourth electrodes displace relative to the backplate as a function of sound pressure incident upon the diaphragm. The first and third electrodes may form a first capacitor and the second and fourth electrodes may form a second capacitor, the capacitance of each which may be a function of the displacement of the diaphragm, and each of which may be biased by an alternating-current voltage waveform.

Abstract: A bias circuit for a capacitive sensor may include a variable impedance element coupled to a capacitor of the capacitive sensor wherein an impedance of the variable impedance element is varied in accordance with a temperature associated with the bias circuit and an active feedback circuit coupled between the variable impedance element and an output of a processing circuit for processing a signal generated by the capacitive sensor and configured to drive the variable impedance element to force a direct-current (DC) voltage level of an output of the capacitive sensor to a desired voltage.

Abstract: A MEMS may include a backplate comprising first and second electrodes electrically isolated from one another and mechanically coupled to the backplate in a fixed relationship relative to the backplate, and a diaphragm configured to mechanically displace relative to the backplate as a function of sound pressure incident upon the diaphragm. The diaphragm may comprise third and fourth electrodes electrically isolated from one another and mechanically coupled to the diaphragm in a fixed relationship relative to the diaphragm such that the third and fourth electrodes mechanically displace relative to the backplate as the function of the sound pressure. The first and third electrodes may form a first capacitor, the second and fourth electrodes may form a second capacitor, and the first capacitor may be configured to sense a displacement of the diaphragm responsive to which the second capacitor may be configured to apply an electrostatic force to the diaphragm to return the diaphragm to an original position.

Abstract: An apparatus includes an integrated circuit (IC) adapted to be powered by a positive supply voltage. The IC includes a charge pump that is adapted to convert the positive supply voltage of the IC to a negative bias voltage. The IC further includes a bidirectional interface circuit. The bidirectional interface circuit includes an amplifier coupled to the negative bias voltage to accommodate a bidirectional input voltage of the IC. The bidirectional interface circuit further includes a comparator coupled to the negative bias voltage to accommodate the bidirectional input voltage of the IC.

Abstract: An apparatus includes an integrated circuit (IC). The IC includes a differencing comparator. The differencing comparator receives a differential input signal. The differencing comparator compares the differential input signal to a threshold value. The differencing comparator includes a transconductance circuit coupled to receive the differential input signal and to provide a differential output signal.

Abstract: The application describes MEMS transducers having a patterned membrane electrode which incorporates a plurality of openings or voids. A conductive element is provided on the surface of the underlying membrane within the opening.

Abstract: Sensing electronics may be used to measure capacitance of components, such as speakers in mobile devices. A sensing circuit may include a charge-sense front end with sine wave excitation, an analog-to-digital conversion block, and a digital demodulator. The component being measured by the sensing electronics may be excited by a high-frequency sine wave excitation. The digitization of the output from the component may be performed using a bandpass filter synchronized with the excitation signal by centering the bandpass filter near (e.g., within 5% of) the frequency of the excitation signal.