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Linearity enhancement of capacitive transducers by auto-calibration using on-chip neutralization capacitors and linear actuation

  • US 9,032,777 B2
  • Filed: 09/16/2011
  • Issued: 05/19/2015
  • Est. Priority Date: 09/16/2011
  • Status: Active Grant
First Claim
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1. A method for automatically calibrating a capacitive transducer to neutralize feed-through capacitance starting from an initial value for a neutralization capacitance, the method comprising:

  • applying no electrostatic force to a proof mass of the capacitive transducer;

    recording a base output value of the capacitive transducer while no electrostatic force is applied to the proof mass;

    applying an electrostatic force F0 to the proof mass of the capacitive transducer;

    recording a first change in the output value of the capacitive transducer between the base output value and a first output value when the electrostatic force F0 is applied to the proof mass;

    applying an electrostatic force n*F0 to the proof mass of the capacitive transducer, where F0 is a fraction of n*F0;

    recording a second change in the output value of the capacitive transducer between the first output value and a second output value when the electrostatic force n*F0 is applied to the proof mass;

    increasing, decreasing or maintaining the neutralization capacitance based on the recorded first and second changes in the output value of the capacitive transducer; and

    repeating the method until a final value for the neutralization capacitance is reached.

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