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Reduced capacitive baseline shift via mixing period adjustments

  • US 10,372,276 B2
  • Filed: 01/06/2017
  • Issued: 08/06/2019
  • Est. Priority Date: 01/06/2017
  • Status: Active Grant
First Claim
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1. A method comprising:

  • driving, onto a first group of a plurality of sensor electrodes, a first capacitive sensing signal having a predefined first sensing frequency;

    acquiring, based on the driven first capacitive sensing signal, first capacitive measurements of resulting signals received by a second group of the plurality of sensor electrodes, wherein acquiring first capacitive measurements comprises applying a first demodulation signal having a predefined first mixing period defined within a sensing period associated with the first sensing frequency;

    driving, onto a third group of the plurality of sensor electrodes, a second capacitive sensing signal having a second sensing frequency different than the first sensing frequency; and

    acquiring, based on the driven second capacitive sensing signal, second capacitive measurements of resulting signals received by a fourth group of the plurality of sensor electrodes,wherein acquiring second capacitive measurements comprises applying a second demodulation signal having a predefined second mixing period within a sensing period associated with the second sensing frequency, the second mixing period different than the first mixing period, andwherein the second mixing period is selected such that a second average current value for the second capacitive measurements has a substantially linear relation to a first average current value for the first capacitive measurements, the linear relation based on the first sensing frequency and the second sensing frequency.

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