Ultra-low power readout circuit with high-voltage bias generation for MEMS accelerometer

A method for operating a low power motion sensing system, comprising:

• providing a motion sensor with a proof mass and cantilever beams, producing acceleration signals with its capacitance change;
• directly coupling output terminals of the motion sensor to an input amplifier of a readout circuit without signal chopping;
• and
• supplying high bias voltages to the motion sensor, where the magnitude of the bias voltage is such that an output signal of the motion sensor is larger than a flicker noise associated with the readout circuit.

A low power motion sensing system, comprising:

• a motion sensor having a proof mass and cantilever beams, producing acceleration signals with its capacitance change;
• a bias circuit interfaced with the motion sensor and operable to supply a positive bias voltage and a negative bias voltage to the motion sensor, where the difference between the magnitude of the positive bias voltage and the magnitude of the negative bias voltage is set to compensate process mismatch in the motion sensor;
• and
• a readout circuit interfaced with the motion sensor, wherein the readout circuit includes an input amplifier directly coupled to output terminals of the motion sensor, and a programmable gain amplifier in series with the input amplifier, and magnitude of the positive and negative bias voltages are such that an output signal of the motion sensor is larger than flicker noise associated with the readout circuit.