Quadrature error compensation circuit for a MEMS gyroscope
AssigneeNXP USA, Inc.
InventorsHugues Beaulaton, Philippe Patrick Calmettes, Thierry Dominique Yves Cassagnes
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Abstract
MEMS gyroscopes are often integrated in modern electronic products for measuring orientation or rotation in those products. However, these MEMS gyroscopes are often inaccurate. The invention provides a compensation circuit to compensate for errors causing a distortion of a measured Coriolis force. The compensation circuit demodulates an input signal provided by the MEMS gyroscope to produce a quadrature signal indicative of the quadrature error and provides a compensation signal to the MEMS gyroscope for actively compensating the quadrature error.
Claims20
A compensation circuit for a MEMS gyroscope configured to produce a gyroscope signal indicative of a rotation, the compensation circuit comprising:
- a demodulator adapted to demodulate the gyroscope signal by using a clock signal to produce a quadrature signal indicative of a quadrature error of the MEMS gyroscope;
- an adjustment unit adapted to adjust a DC compensation signal in dependence of the quadrature signal to produce an adjusted DC compensation signal, wherein the adjustment unit is configured to determine a sign of the quadrature signal, the sign being a positive sign or a negative sign, subtract an adjustment value from the DC compensation signal to produce the adjusted DC compensation signal when the quadrature signal is the positive sign, and add the adjustment value to the DC compensation signal to produce the adjusted DC compensation signal when the quadrature signal is the negative sign;
- and
- an output unit adapted to output the adjusted DC compensation signal to the MEMS gyroscope to compensate for the quadrature error.
A system adapted to measure a Coriolis force comprising:
- a first device adapted to measure a first Coriolis force comprising
- a first MEMS gyroscope comprising a first mass adapted to vibrate along a first trajectory, the first MEMS gyroscope being configured to produce a first Coriolis signal indicative of the Coriolis force, wherein the first Coriolis signal comprises a quadrature error;
- a first compensation circuit comprising:
- a first demodulator adapted to demodulate the first Coriolis signal by using a first clock signal to produce a first quadrature signal indicative of a first quadrature error;
- a first adjustment unit adapted to adjust a first DC compensation signal in dependence of the first quadrature signal to produce an adjusted first DC compensation signal, wherein the first adjustment unit is configured to determine a sign of the first quadrature signal, the sign being a positive sign or a negative sign, subtract an adjustment value from the first DC compensation signal to produce the adjusted first DC compensation signal when the first quadrature signal is the positive sign, and add the adjustment value to the first DC compensation signal to produce the adjusted first DC compensation signal when the first quadrature signal is the negative sign;
- and
- a first output unit adapted to output the adjusted first DC compensation signal to the first MEMS gyroscope to compensate for the first quadrature error.
A method for compensating a quadrature error of a MEMS gyroscope, the method comprising:
- demodulating an input signal provided by the MEMS gyroscope by using a clock signal to produce a quadrature signal indicative of a quadrature error;
- adjusting a DC compensation signal in dependence of the quadrature signal to produce an adjusted DC compensation signal, the adjusting operation comprising:
- determining the sign of the quadrature signal;
- subtracting the adjustment value from the DC compensation signal to produce the adjusted DC compensation signal when the quadrature signal is the positive sign;
- and
- adding the adjustment value to the DC compensation signal to produce the adjusted DC compensation signal when the quadrature signal is the negative sign;
- and
- providing the adjusted DC compensation signal to the MEMS gyroscope to compensate for a quadrature error of the MEMS gyroscope.
Dependencies are inferred from the claim text.