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AUTOMATIC POWER REDUCTION IN PHOTOPLETHYSMOGRAPHY AND PULSE OXIMETRY SYSTEMS

  • US 20170281066A1
  • Filed: 03/30/2016
  • Published: 10/05/2017
  • Est. Priority Date: 03/30/2016
  • Status: Active Grant
First Claim
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1. An apparatus comprising:

  • a transmit circuit including a light source;

    a receive circuit including a photodetector and a transimpedance amplifier coupled to the photodetector; and

    a calibration circuit coupled to the transmit circuit and the receive circuit, the calibration circuit including,a current controller to set an operational current of the light source to a minimum value that results in a target output voltage of the receive circuit, the current controller comprising a reference comparator to generate a first comparison signal based on a calibration output voltage of the receive circuit and a reference voltage, the current controller further comprising a counter coupled to the reference comparator, the counter to generate a counter value based on the first comparison signal,a local oscillator coupled to the counter, anda logic gate coupled to the reference comparator, the logic gate to generate a completion notification in response to the calibration output voltage of the receive circuit exceeding the reference voltage, wherein a gain of the transimpedance amplifier is to remain substantially constant during calibration of the receive circuit.

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