Sensing apparatus having a light sensitive detector field
View Patent ↗A sensing apparatus includes a sensor and a processor. The sensor includes at least one light sensitive detector. The processor determines a first control value to control a voltage differential across the at least one light sensitive detector, and compares the first control value with a reference value associated with a reference temperature. Based on the comparison, the processor provides adjustment information for adjusting at least one output of the sensing apparatus, and an operating parameter of the sensing apparatus other than the voltage differential.
1. A device comprising:
a single photon avalanche detector (SPAD);
a voltage regulator coupled to the SPAD;
a counter having an input coupled to an output of the SPAD; and
a controller configured to perform a calibration test by:
modifying a voltage across the SPAD by controlling the voltage regulator to cycle through a plurality of output voltages;
determining, with the counter, a plurality of counts, wherein each count of the plurality of counts is associated with a respective voltage of the plurality of output voltages;
selecting a first voltage of the plurality of output voltages based on the plurality of counts;
compare the first voltage with a reference voltage; and
determining a temperature drift based on the comparison.
2. The device of claim 1 , further comprising an oscillator, wherein the controller is further configured to, during the calibration test, adjust a frequency of the oscillator based on the temperature drift.
3. The device of claim 2 , wherein the controller is configured to adjust the frequency of the oscillator by using a look up table.
4. The device of claim 1 , further comprising a non-volatile memory, wherein a value associated with the reference voltage is stored in the non-volatile memory.
5. The device of claim 1 , wherein the SPAD comprises:
a p-n junction coupled between a first supply node and a first node;
a transistor coupled between a second supply node and the first node; and
an inverter coupled between the first node and the output of the SPAD.
6. The device of claim 5 , wherein the voltage regulator is coupled to the first supply node.
7. The device of claim 5 , wherein the voltage regulator is coupled to the second supply node.
8. The device of claim 1 , further comprising a plurality of SPADs, wherein the plurality of SPADs comprises the SPAD, and wherein the plurality of SPADs are coupled to the counter via an OR-TREE.
9. The device of claim 1 , wherein the controller is configured to perform the calibration test at predetermined time intervals.
10. The device of claim 1 , further comprising a light source driver configured to control a light source, wherein the controller is further configured to control the light source driver during the calibration test.
11. The device of claim 1 , wherein:
modifying the voltage across the SPAD comprises increasing the voltage across the SPAD; and
selecting the first voltage comprises determining a second voltage at which the SPAD is firing, wherein the first voltage is equal to the second voltage plus a predetermined voltage.
12. A method comprising:
cycling through a plurality of voltage across a single photon avalanche detector (SPAD);
determining, with a counter coupled to the SPAD, a plurality of counts, wherein each count of the plurality of counts is associated with a respective voltage of the plurality of voltages;
selecting a first voltage of the plurality of voltages based on the plurality of counts;
comparing the first voltage with a reference voltage; and
determining a temperature drift based on the comparison.
13. The method of claim 12 , further comprising adjusting a frequency of an oscillator based on the temperature drift.
14. The method of claim 13 , wherein adjusting the frequency of the oscillator comprises using a look up table.
15. The method of claim 13 , wherein adjusting the frequency of the oscillator comprises adjusting the frequency of the oscillator to avoid harmonics with one or more 4G frequency bands.
16. The method of claim 12 , further comprising storing the reference voltage into non-volatile memory.
17. The method of claim 12 , wherein:
cycling through the plurality of voltages comprises increasing the voltage across the SPAD; and
selecting the first voltage comprises determining a second voltage at which the SPAD is firing, wherein the first voltage is equal to the second voltage plus a predetermined voltage.
18. The method of claim 12 , further comprises determining a distance to an object by determining a first distance, wherein the distance to the object is equal to the first distance plus 1/x times (the reference voltage minus the first voltage), wherein x is a predetermined constant.
19. The method of claim 18 , wherein the distance to the object is equal to the first distance plus 1/x times (the reference voltage minus the first voltage) when a current temperature is greater than or equal to a predetermined threshold, and wherein the distance to the object is equal to the first distance plus 1/y times (the reference voltage minus the first voltage) when a current temperature is lower than the predetermined threshold, wherein y is a predetermined constant.
20. The method of claim 19 , wherein y is greater than x.
21. A device comprising:
means for cycling through a plurality of voltage across means for sensing light;
means for determining a plurality of counts received from the means for sensing light, wherein each count of the plurality of counts is associated with a respective voltage of the plurality of voltages;
means for selecting a first voltage of the plurality of voltages based on the plurality of counts;
means for comparing the first voltage with a reference voltage; and
means for determining a temperature drift based on the comparison.