Noise reduction method with chopping for a merged MEMS accelerometer sensor
AssigneeFairchild Semiconductor Corporation
InventorsJonathan Adam Kleks, Ion Opris, Justin Seng
Life of this patent
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Abstract
An apparatus includes a capacitance-to-voltage converter circuit configured to be electrically coupled to a micro-electromechanical system (MEMS) sensor circuit. The capacitance-to-voltage converter circuit includes a differential chopping circuit path configured to receive a differential MEMS sensor output signal and invert a polarity of the differential chopping circuit path, and a differential sigma-delta analog to digital converter (ADC) circuit configured to sample the differential MEMS sensor output signal and provide a digital signal representative of a change in capacitance of the MEMS sensor.
Claims22
An apparatus comprising:
- a capacitance-to-voltage converter circuit configured to be electrically coupled to a micro-electromechanical system (MEMS) sensor circuit, the capacitance-to-voltage converter circuit including:
- a differential chopping circuit path configured to receive a differential MEMS sensor output signal and invert a polarity of the differential chopping circuit path;
- and
- a differential sigma-delta analog to digital converter (ADC) circuit configured to sample the differential MEMS sensor output signal and provide a digital signal representative of a change in capacitance of the MEMS sensor.
An apparatus comprising:
- a capacitance-to-voltage converter circuit configured to be electrically coupled to a MEMS sensor circuit, the capacitance-to-voltage converter circuit including:
- a differential circuit path configured to receive a differential MEMS sensor output signal;
- a differential sigma-delta ADC circuit configured to sample the differential MEMS sensor output signal and provide a digital signal representative of a change in capacitance of the MEMS sensor, wherein the differential sigma-delta ADC circuit includes a comparator circuit;
- and
- a pseudo-random noise generator circuit electrically coupled to the comparator circuit and configured to apply dither noise to an input of the comparator circuit.
A method comprising:
- sensing an output of a micro-electromechanical system (MEMS) sensor to create a differential sensor output signal;
- applying the output of the MEMS sensor to a differential chopping circuit path, wherein a polarity of the differential chopping circuit path is inverted at timed intervals;
- and
- sampling the chopped MEMS sensor output signal with a differential sigma-delta analog to digital converter (ADC) circuit to generate a digital signal representative of a change in capacitance of the MEMS sensor.
Dependencies are inferred from the claim text.