Apparatus, system, and method for automatic power reduction in photoplethysmography and pulse oximetry systems
First Claim
Patent Images
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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Abstract
Systems, apparatuses and methods may provide for a transmit circuit including a light source and a receive circuit including a photodetector and a transimpedance amplifier (TIA) coupled to the photodetector. Additionally, a calibration circuit may be coupled to the transmit circuit and the receive circuit, wherein the calibration circuit includes 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. In one example, the gain of the TIA remains substantially constant during calibration of the receive circuit.
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Citations
13 Claims
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1. An apparatus comprising:
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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, and a 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. - View Dependent Claims (2, 3, 4)
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5. An apparatus comprising:
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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, wherein a gain of the transimpedance amplifier is to remain substantially constant during calibration of the receive circuit, the current controller including; a reference comparator to generate a first comparison signal based on a calibration output voltage of the receive circuit and a reference voltage, and a counter coupled to the reference comparator, the counter to generate a counter value based on the first comparison signal; and a 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. - View Dependent Claims (6, 7, 8, 9)
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10. A method comprising:
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transmitting outbound light from a light source of a transmit circuit; receiving inbound light at a photodetector of a receive circuit; amplifying, by a transimpedance amplifier of the receive circuit, an analog signal associated with the inbound light; generating, by a reference comparator, a comparison signal based on a calibration output voltage of the receive circuit and a reference voltage; generating, by a counter, a counter value based on the comparison signal; generating, by a logic gate, a completion notification in response to the calibration output voltage of the receive circuit exceeding the reference voltage; and setting, by a calibration circuit, an operational current of the light source to a minimum value that results in a target output voltage of the receive circuit, wherein the gain of the transimpedance amplifier remains substantially constant during calibration of the receive circuit. - View Dependent Claims (11, 12, 13)
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Specification