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Methods and apparatus for improving remote NFC device detection using a low power oscillator circuit

  • US 9,698,872 B2
  • Filed: 06/18/2013
  • Issued: 07/04/2017
  • Est. Priority Date: 06/18/2013
  • Status: Expired due to Fees
First Claim
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1. A method of wireless communications, comprising:

  • monitoring frequency oscillations associated with a near field communication (NFC) antenna and a matching network using a calibrated low power oscillator (LPO) connected to the NFC antenna, wherein the monitoring comprises;

    generating the frequency oscillations using the LPO; and

    counting a number of occurrences of the frequency oscillations using a frequency counter connected to the LPO, wherein the frequency oscillations are at a frequency which is a function of an impedance of the NFC antenna;

    determining that the number of occurrences of the frequency oscillations is greater than a frequency deviation threshold from a reference frequency;

    waking up an NFC chip and a crystal oscillator coupled to the NFC antenna and matching network in response to the determination; and

    performing a NFC polling procedure using the NFC chip and the crystal oscillator to determine whether the frequency deviation is based on the presence of a remote NFC device in response to the determination.

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