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Electric field attraction minimization circuit

  • US 5,511,420 A
  • Filed: 12/01/1994
  • Issued: 04/30/1996
  • Est. Priority Date: 12/01/1994
  • Status: Expired due to Term
First Claim
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1. A sensor comprising:

  • a sensing differential capacitor having a first sense electrode, a second sense electrode, and a third sense electrode, with the third sense electrode forming a first sense capacitor of the sensing differential capacitor with the first sense electrode and a second sense capacitor of the sensing differential capacitor with the second sense electrode, and with the capacitances of the first sense capacitor and the second sense capacitor being variable in response to a force applied to the sensor;

    means for coupling the first sense electrode to a first carder signal and the second sense electrode to a second carrier signal of the same frequency, with the first carder signal being 180 degrees out of phase with the second carrier signal;

    a buffer having an input coupled to the third sense electrode; and

    a low-pass filter coupled to the first sense electrode, the second sense electrode, and the output of the buffer, so that the filter is disposed between the first sense electrode and the output of the buffer and between the second sense electrode and the output of the buffer.

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