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Mutual capacitance sensing circuits, methods and systems

  • US 9,013,195 B2
  • Filed: 07/27/2011
  • Issued: 04/21/2015
  • Est. Priority Date: 08/23/2010
  • Status: Active Grant
First Claim
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1. A capacitance sensing system, comprising:

  • a first selection circuit that couples N electrodes of a first electrode set to a capacitance sense circuit, wherein the first selection circuit couples the N electrodes to the capacitance sense circuit in a first sense portion of a sensing operation, and further couples L electrodes of the first electrode set to a signal generator circuit in a second sense portion of the sensing operation; and

    a second selection circuit that couples M electrodes of a second electrode set, substantially simultaneously, to the signal generator circuit as a group to induce current in the N electrodes by mutual capacitance between the M and N electrodes;

    wherein N is at least one, and M>

    N, wherein the second selection circuit couples the M electrodes of the second electrode to the signal generator circuit in the first sense portion, and further couples K electrodes of the second electrode set to the capacitance sense circuit in the second sense portion, and wherein K is at least one, and L>

    K.

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