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Low-power activation circuit with motion sensor

  • US 9,419,611 B2
  • Filed: 07/27/2015
  • Issued: 08/16/2016
  • Est. Priority Date: 01/14/2011
  • Status: Active Grant
First Claim
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1. An activation circuit, comprising:

  • a motion sensor configured to output a signal comprising a differential signal proportional to a measured quantity;

    a comparator configured to receive the differential signal from the motion sensor and to generate a comparator signal from the differential signal;

    a digital logic element coupled to an output of the comparator and configured to generate a digital signal from the comparator signal;

    a digital storage element configured to store one or more previous digital signals;

    a difference detector, wherein in an operating phase the difference detector is configured to measure a difference between the digital signal from the digital logic element and a previous digital signal from the digital storage element and to output a difference signal comprising information concerning a magnitude of the difference, wherein if the difference is larger than a digital reference level, the difference detector causes an activation signal generator to generate an activation signal that awakens a system from a sleep; and

    wherein in a low power standby phase, digital signals are stored in the digital storage element.

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