Cirrus Logic Inc.

Cirrus Logic International Semiconductor Limited

James Thomas Deas

John Paul Lesso

Toru Ido

Scott Lyall Cargill

Paul Wilson

Emmanuel Philippe Christian Hardy

Hynek Saman

Jean Pierre Lasseuguette

Axel Thomsen

John Laurence Pennock

Graeme G Mackay

Stephen Timothy Hodapp

Jaimin A Mehta

Marek Sebastian Piechocinski

Vivek Saraf

Brian Parker Chesney

Mucahit Kozak

Ian Johnson Smith

Mark Hesketh

Colin Wei Hong Chung

Sven Soell

Emmanuel Hardy

A circuit may include a two-stage feedforward compensated operational transconductance integrated amplifier, and the two-stage feedforward compensated operational transconductance integrated amplifier may include an input terminal, an output terminal, a signal path between the input terminal and the output terminal, the signal path comprising a first signal path gain stage and a second signal path gain stage, and ripple rejection circuitry coupled between the input terminal and an intermediate node of the signal path located between the first signal path gain stage and the second signal path gain stage. The ripple rejection circuitry may include a first ripple rejection circuitry gain stage coupled at its input to the input terminal and coupled at its output to an input terminal of a chopper circuit, a notch filter coupled at its input to an output terminal of the chopper circuit, and a second ripple rejection circuitry gain stage coupled at its input to an output terminal of the notch filter and coupled at its output to the intermediate node.

Operational amplifier for use in coulomb counter circuit

Coulomb counter circuitry operable in a first mode of operation and a second mode of operation, the coulomb counter circuitry comprising: first analog to digital converter (ADC) circuitry configured to generate a first ADC output signal indicative of a current through a load coupled to the coulomb counter circuitry; second analog to digital converter (ADC) circuitry; offset correction circuitry; and accumulator circuitry configured to generate a signal indicative of a cumulative amount of charge transferred to the load, wherein in the second mode of operation, the coulomb counter circuitry is operable to enable the second ADC circuitry and to generate an offset correction factor based at least in part on a second ADC output signal output by the second ADC circuitry, and wherein in subsequent operation of the coulomb counter circuitry in the first mode of operation, the offset correction circuitry applies the offset correction factor to the first ADC output signal.

Coulomb counter circuitry

Micro-electro-mechanical system (MEMS) devices are disclosed, including a MEMS device comprising a semiconductor die including integrated circuitry, a structure mounted on the semiconductor die and covering at least a portion of the circuitry, the structure defining a space between the structure and the at least a portion of the circuitry, and a transducer including a membrane, the transducer located outside of the space.

MEMS device

The application describes a MEMS transducer in which first and second conductive elements of a capacitor are both provided on the membrane. The membrane is shaped such that the first and second conductive elements are displaced relative to each other when the flexible membrane deflects in response to a pressure differential across the membrane. For example the membrane may be corrugated.

MEMS device and process

This applications relates to methods and apparatus for amplifying signals from capacitive transducers, in particular MEMS transducers such as MEMS capacitive microphones. An amplifier circuit has a signal node for receiving the input signal, a transducer biasing node for outputting a transducer bias voltage for biasing the capacitive transducer, and a voltage buffer configured to generate a buffered bias voltage at a buffer node. An amplifier arrangement is configured to receive the input signal from the signal node and the buffered bias voltage. The amplifier circuit comprises a signal path for supplying the buffered bias voltage to the transducer biasing node via a first capacitance, and the amplifier arrangement comprises a feedback resistor network configured such that: a change in input signal with respect to the buffered bias voltage results in a change in the output signal with respect to the buffered bias voltage with a gain greater than one; and a change in the buffered bias voltage results in a change in the output signal with a gain equal to one.

MEMS transducer amplifiers

An amplifier circuit has a transducer biasing node for outputting a transducer bias voltage for biasing the capacitive transducer and a signal node for receiving the input signal. An amplifier arrangement comprising a feedback resistor network provides an amplified output signal. A voltage buffer provides a buffered bias voltage at a buffer node which is connected to a terminal of the feedback resistor network, to at least partly define the quiescent level of the output signal. The buffer node is electrically coupled to the transducer biasing node via a capacitance which may form part of a bias filter.

The present disclosure relates to a protection system for protecting a MEMS transducer of a MEMS device from electrostatic capture, wherein the MEMS transducer is operable in a normal-sensitivity, mode and in a reduced-sensitivity mode. The protection system comprises: an overload detector for detecting an overload condition arising as a result of an excessive sound pressure level at the MEMS transducer; a signal estimator configured to generate an estimate of a sound pressure level at the MEMS transducer; and a controller configured, in response to detection by the overload detector of an overload condition, to: disable an output of the MEMS transducer; and after a delay of a first predetermined period of time: cause the MEMS transducer to operate in the reduced-sensitivity mode; enable the output of the MEMS transducer; and cause the MEMS transducer to return to the normal-sensitivity mode if the estimate of the sound pressure level generated by the signal estimator while the MEMS transducer is operating in the reduced-sensitivity mode is below a safe sound pressure level threshold for a second predetermined period of time.

MEMS devices

MEMS devices are disclosed including a MEMS microphone device comprising a first transducer adjoining a sound port, a second transducer not adjoining a sound port, a housing defining a shared volume for the first and second transducers, and circuitry arranged to combine a first signal from the first transducer and a second signal from the second transducer to produce an output signal.

The present disclosure relates to a micro electro-mechanical system (MEMS) device comprising a fixed electrode, a moveable electrode that is moveable with respect to the fixed electrode and an output terminal for outputting a transducer output signal indicative of a capacitance between the fixed electrode and the moveable electrode. A package is provided which houses the fixed electrode and the moveable electrode, the package defining a first volume on a first side of the moveable electrode. The moveable electrode is moveable within the first volume in response to sound or pressure waves incident on the moveable electrode. A power dissipation element is disposed within the package. The power dissipation element is configured to receive a generated stimulus signal and to dissipate heat into the first volume so as to modulate the pressure of air within the first volume in accordance with the received generated stimulus signal.

MEMs devices

This application relates to an integrated circuit die () comprising a MEMS transducer structure () integrated with associated electronic circuitry (). The electronic circuitry comprises a plurality of transistors and associated interconnections and is formed in a first area () of the die from a first plurality () of layers, e.g. formed by CMOS metal () and dielectric () layers and possibly doped areas () of substrate (). The MEMS transducer structure is formed in a second area () of the die and is formed, at least partly, from a second plurality () of layers which are separate to the first plurality of layers. At least one filter circuit () is formed from said second plurality of layers overlying the plurality of transistors of the electronic circuitry (). The second plurality of layers comprise at least a first metal layer () which is patterned to form a first electrode of the MEMS transducer and at least a resistor, capacitor electrode or inductor element () of the filter circuit.

Integrated MEMS transducer and circuitry

A system may include control circuitry for detecting a plosive event associated with a microphone transducer and in response to the plosive event, causing restoration of acoustic sense operation of the microphone transducer and a processing circuit associated with the microphone transducer. A system for configuring a filter having at least two frequency response configurations to achieve an effective frequency response configuration intermediate to the at least two frequency response configurations may include control circuitry for rapidly switching between the at least two frequency response configurations such that a weighted average frequency response of the filter corresponds to the effective frequency response configuration.

Systems and methods for restoring microelectromechanical system transducer operation following plosive event

The application describes a MEMS transducer in which first and second conductive elements of a capacitor are both provided on the membrane. The membrane is shaped that the first and second conductive elements are displaced relative to each other when the flexible membrane deflects in response to a pressure differential across the membrane. For example the membrane may be corrugated.

This application relates to circuitry for processing sense signals generated by MEMS capacitive transducers for compensating for distortion in such sense signals. The circuitry has a signal path between an input () for receiving the sense signal and an output () for outputting an output signal based on said sense signal. Compensation circuitry () is configured to monitor the signal at a first point along the signal path and generate a correction signal (Scorr); and modify the signal at at least a second point along said signal path based on said correction signal. The correction signal is generated as a function of the value of the signal at the first point along the signal path so as to introduce compensation components into the output signal that compensate for distortion components in the sense signal. The first point in the signal path may be before or after the second point in the signal path. The monitoring may be performed in an analogue or a digital part of the signal path and in either case the modification may be applied in an analogue or a digital part of the signal path.

Signal processing for MEMS capacitive transducers

This application relates to circuitry for processing sense signals generated by MEMS capacitive transducers for compensating for distortion in such sense signals. The circuitry has a signal path between an input () for receiving the sense signal and an output () for outputting an output signal based on said sense signal. Compensation circuitry () is configured to monitor the signal at a first point along the signal path and generate a correction signal (S); and modify the signal at at least a second point along said signal path based on said correction signal. The correction signal is generated as a function of the value of the signal at the first point along the signal path so as to introduce compensation components into the output signal that compensate for distortion components in the sense signal. The first point in the signal path may be before or after the second point in the signal path. The monitoring may be performed in an analogue or a digital part of the signal path and in either case the modification may be applied in an analogue or a digital part of the signal path.

Amplifier arrangements for read-out of MEMS capacitive transducers, such as low-noise amplifiers. An amplifier circuit has first and second MOS transistors, with the gate of the first transistor driven by the input signal, and the gate of the second transistor driven by a reference. The sources of the first and second transistors are connected via an impedance. Modulation circuitry is arranged to monitor a signal with a value that varies with the input signal and to modulate the back-bias voltage between the bulk and source terminals of the first and second transistors with the applied modulation being equal for each transistor and based on said monitored signal. The back-bias of the first transistor can be increase to extend the input range of the transistor in situations where the input signal may otherwise result in signal clipping, while avoiding noise and power issues for other input signal levels. By applying an equal modulation to the back-bias of each transistor, there is no substantial modulation of the output signal.

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Edinburgh, United Kingdom

James Thomas Deas