Method and apparatus for spectrally-corrected ambient light sensor
AssigneeSilicon Laboratories Inc.
InventorsWayne T. Holcombe, Miroslav Svajda
Life of this patent
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Abstract
In one embodiment, a method includes receiving outputs from multiple photodetectors, calculating a first ratio between first and second such outputs, calculating a second ratio between the first output and a difference corresponding to a flicker noise component obtained from the second output, and determining a contribution from multiple illumination types based at least in part on the first and second ratios. The method may also include obtaining multiple correction coefficients based at least in part on the determined contribution, and in turn determining an ambient light type present in proximity to the photodetectors using the correction coefficients and the first and second outputs.
Claims19
An apparatus comprising:
- a dual photodetector having a first photodetector configured for a visible light spectrum and a second photodetector configured for an infrared light spectrum, wherein the first and second photodetectors are coupled at a common node, and the first photodetector is stacked above the second photodetector;
- a selector coupled to an output of the first and second photodetectors;
- and
- an analog-to-digital converter (ADC) coupled to the selector and having a bipolar input to receive a current of a first polarity and a current of a second polarity from the selector, the current of the first polarity to be received from the second photodetector and the current of the second polarity to be received from the first photodetector.
A method comprising:
- receiving a first output from a first photodetector configured for a visible light spectrum and a second output from a second photodetector configured for an infrared light spectrum;
- calculating a first ratio between the first output and the second output;
- calculating a second ratio between the first output and a difference corresponding to a flicker noise component obtained from the second output;
- determining a contribution from multiple illumination types based at least in part on the first and second ratios;
- and
- determining an ambient light type present in proximity to the first and second photodetectors using first and second correction coefficients and the first and second outputs.
A portable device comprising:
- a processor to perform application program instructions;
- a transceiver to transmit and receive radio frequency (RF) signals;
- a display to display information to a user;
- a dual photodetector structure having a first photodetector to detect energy in a visible light spectrum, a second photodetector to detect energy in an infrared light spectrum, a switching circuit to control coupling of the first and second photodetectors to a selection circuit, and an analog-to-digital converter (ADC) coupled to the selection circuit to receive and convert a first current of a first polarity received from the second photodetector and a second current of a second polarity received from the first photodetector;
- and
- a controller coupled to the dual photodetector structure to receive digitized information corresponding to the first and second currents and to determine an ambient light type based on a photopic illumination value calculated using at least one correction coefficient obtained based at least in part on the first and second currents.
Dependencies are inferred from the claim text.