Gyroscope quadrature cancellation
AssigneeInvenSense, Inc.
InventorVadim Tsinker
Life of this patent
Estimating the term…
Abstract
A microelectromechanical system (MEMS) gyroscope includes a MEMS structure that outputs a capacitive signal that includes both a Coriolis signal used to determine an angular velocity and a quadrature signal 90 degrees out-of-phase with the Coriolis signal. A capacitance to voltage (C2V) amplifier receives and amplifies the capacitive signal for further processing. Quadrature cancellation circuitry processes the output of the C2V amplifier to isolate the quadrature signal and generate a signal to control variable capacitors coupled to the C2V amplifier input in a manner that removes the quadrature signal from the C2V amplifier output.
Claims20
A method for cancelling a quadrature component of a sensed signal of a microelectromechanical system (MEMS) gyroscope, comprising:
- receiving, at an input of a capacitance-to-voltage (C2V) amplifier, the sensed signal, wherein the sensed signal corresponds to a movement of one or more components of a MEMS structure;
- outputting, from the C2V amplifier, a C2V output signal;
- extracting, from the C2V output signal, a quadrature portion of the C2V output signal;
- integrating the quadrature portion of the C2V output signal;
- digitizing the integrated quadrature portion;
- generating, by digital processing circuitry, a variable capacitor control signal based on the digitized integrated quadrature portion, wherein the variable capacitor control signal is generated to reduce the quadrature portion of the C2V output signal;
- and
- providing, from the digital processing circuitry to one or more variable quadrature cancellation capacitors, the variable capacitor control signal, wherein the one or more variable quadrature cancellation capacitors are coupled to the C2V amplifier to modify the received sensed signal, and wherein the quadrature component of the sensed signal is cancelled based on the capacitances of the one or more variable quadrature cancellation capacitors.
A microelectromechanical system (MEMS) gyroscope, comprising:
- a MEMS structure, wherein a sensed capacitive signal associated with the MEMS structure changes based on a sensed angular velocity;
- a capacitance-to-voltage (C2V) amplifier, comprising an input coupled to the MEMS structure to receive the sensed capacitive signal;
- a demodulator coupled to an output of the C2V amplifier, wherein the demodulator is configured to demodulate a portion of the output of the C2V amplifier associated with a quadrature portion of the sensed capacitive signal;
- an integrator coupled to the demodulator to integrate an output signal of the demodulator;
- an analog-to-digital converter (ADC) coupled to the demodulator to digitize an output of the integrator;
- digital processing circuitry coupled to an output of the ADC, wherein the digital processing circuitry is configured to generate a variable capacitor control signal based on the output of the ADC, wherein the variable capacitor control signal is generated to reduce the quadrature portion;
- and
- at least one variable capacitor coupled to an output of the ADC and the input of the C2V amplifier, wherein the at least one variable capacitor receives the variable capacitor control signal from the digital processing circuitry, and wherein the quadrature portion of the sensed capacitive signal is cancelled based on a capacitance of the at least one variable capacitor.
A processing circuitry of a microelectromechanical system (MEMS) gyroscope, comprising:
- a capacitance-to-voltage (C2V) amplifier, comprising an input coupled to an output of a MEMS structure to receive a sensed capacitive signal from the MEMS structure;
- a demodulator coupled to an output of the C2V amplifier, wherein the demodulator is configured to demodulate a portion of the output of the C2V amplifier associated with a quadrature portion of the sensed capacitive signal;
- an integrator coupled to the demodulator to integrate an output signal of the demodulator;
- an analog-to-digital converter (ADC) coupled to the demodulator to digitize an output of the integrator;
- digital processing circuitry coupled to an output of the ADC, wherein the digital processing circuitry is configured to generate a variable capacitor control signal based on the output of the ADC, wherein the variable capacitor control signal is generated to reduce the quadrature portion;
- and
- at least one variable capacitor coupled to an output of the digital processing circuitry and the input of the C2V amplifier, wherein the at least one variable capacitor receives the variable capacitor control signal from the digital processing circuitry, and wherein the quadrature portion of the sensed capacitive signal is cancelled based on a capacitance of the at least one variable capacitor.
Dependencies are inferred from the claim text.