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Capacitance sensing circuit for a pressure sensor

  • US 7,516,669 B2
  • Filed: 01/16/2008
  • Issued: 04/14/2009
  • Est. Priority Date: 10/18/2004
  • Status: Expired due to Fees
First Claim
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1. A capacitance sensing circuit for a pressure sensor having a sensor membrane and a compensation membrane, the circuit comprisinga controller;

  • anda charge amplifier, a charge injector and two switches, in signal communication with the controller, the charge amplifier connected to the switches via a sensor capacitor Cs in parallel with a reference capacitor Cr in parallel with a parasitic capacitance Cp to ground, the charge injector and charge amplifier arranged in parallel connection between the capacitors and controller, the controller configured to determine a charge imbalance indicative of a pressure difference between the sensor and compensation membranes.

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