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Switched capacitor transducer

  • US 5,343,766 A
  • Filed: 02/25/1992
  • Issued: 09/06/1994
  • Est. Priority Date: 02/25/1992
  • Status: Expired due to Fees
First Claim
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1. A capacitive transducer comprising:

  • first and second variable capacitors comprising first and second fixed capacitor electrodes and a common capacitor electrode interposed between the first and second electrodes, the common electrode being displaceable from a rest position to vary the capacitances of the capacitors as a function of a parameter being measured;

    capacitance sensing means for generating an output voltage which is a function of the sensed parameter and having inverting and non-inverting inputs tied to a biasing voltage;

    first switch means for connecting the first and second electrodes to first and second dc reference voltages and for coupling the input of the capacitance sensing means to the common electrode to thereby couple the biasing voltage to the common electrode;

    second switch means for connecting the first and second electrodes to a variable dc reference voltage intermediate the first and second reference voltages and connecting the common electrode to the non-inverting input of the capacitance sensing means;

    means for opening and closing the first and second switch means in non-overlapping sequence; and

    an attenuating circuit responsive to the output voltage for generating the said variable reference voltage.

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