Optical receiver chain for components of a photoplethysmograph signal
First Claim
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1. Circuitry for an optical receiver, comprising:
- a photo detector to;
receive ambient light that has an ambient intensity and, in response thereto, output a first signal on at least one first line having a first magnitude that represents the ambient intensity; and
receive pulsed light that has a pulsed intensity and, in response thereto, output a second signal on the at least one first line having a second magnitude that represents the pulsed intensity without the ambient intensity, the second magnitude of the second signal having a pleth DC component and a pleth AC component; and
a demodulation circuit coupled to the photo detector to;
sample and hold the first signal, and output a third signal on at least one second line whose magnitude represents the first magnitude of the first signal; and
sample and hold the second signal, and output a fourth signal on the at least one second line whose magnitude represents the second magnitude of the second signal, the magnitude of the fourth signal having a pleth DC component that represents the pleth DC component of the second signal, and a pleth AC component that represents the pleth AC component of the second signal.
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Abstract
The circuitry of an optical receiver reduces the ambient DC component and the pleth DC component to leave a pleth signal with substantially only a pleth AC component. The circuitry also provides gain control and can provide transmit power control to change the range of the pleth AC component to occupy a desired input range of an analog-to-digital converter.
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Citations
20 Claims
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1. Circuitry for an optical receiver, comprising:
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a photo detector to; receive ambient light that has an ambient intensity and, in response thereto, output a first signal on at least one first line having a first magnitude that represents the ambient intensity; and receive pulsed light that has a pulsed intensity and, in response thereto, output a second signal on the at least one first line having a second magnitude that represents the pulsed intensity without the ambient intensity, the second magnitude of the second signal having a pleth DC component and a pleth AC component; and a demodulation circuit coupled to the photo detector to; sample and hold the first signal, and output a third signal on at least one second line whose magnitude represents the first magnitude of the first signal; and sample and hold the second signal, and output a fourth signal on the at least one second line whose magnitude represents the second magnitude of the second signal, the magnitude of the fourth signal having a pleth DC component that represents the pleth DC component of the second signal, and a pleth AC component that represents the pleth AC component of the second signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of operating circuitry for an optical receiver, the method comprising:
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receiving ambient light that has an ambient intensity and, in response thereto, outputting a first signal having a first magnitude that represents the ambient intensity; receiving pulsed light that has a pulsed intensity and, in response thereto, outputting a second signal having a second magnitude that represents the pulsed intensity without the ambient intensity, the second magnitude of the second signal having a pleth DC component and a pleth AC component; sampling and holding the first magnitude of the first signal, and outputting a third signal having a magnitude that represents the first magnitude of the first signal; and sampling and holding the second magnitude of the second signal, and outputting a fourth signal with a magnitude that represents the second magnitude of the second signal, the magnitude of the fourth signal having a pleth DC component that represents the pleth DC component of the second signal, and a pleth AC component that represents the pleth AC component of the second signal. - View Dependent Claims (19, 20)
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Specification