System with a SPAD-based semiconductor device having dark pixels for monitoring sensor parameters
A semiconductor device may include a plurality of single-photon avalanche diodes (SPADs). The semiconductor device may include sensing single-photon avalanche diodes that are sensitive to incident light and dark single-photon avalanche diodes that are shielded from incident light. The dark single-photon avalanche diodes may be used to measure one or more parameters for the semiconductor device such as breakdown voltage, dark count rate, and quench resistance. Processing circuitry may optimize a bias voltage for the semiconductor device based on information regarding one or more sensor parameters obtained using the dark single-photon avalanche diodes.
1. A system, comprising:
a semiconductor device that includes sensing single-photon avalanche diodes and a shielded single-photon avalanche diode; and
processing circuitry that is coupled to the shielded single-photon avalanche diode, wherein the processing circuitry is configured to update a bias voltage for the sensing single-photon avalanche diodes based on feedback from the shielded single-photon avalanche diode and wherein the processing circuitry comprises a current source that is configured to apply a measurement current to the shielded single-photon avalanche diode.
2. The system defined in claim 1 , wherein the processing circuitry comprises:
an error amplifier having first and second inputs, wherein the first input is coupled to the shielded single-photon avalanche diode and the second input is coupled to a target over voltage.
3. The system defined in claim 2 , wherein the processing circuitry is configured to update the bias voltage for the sensing single-photon avalanche diodes based on an output from the error amplifier.
4. A system, comprising:
a semiconductor device that includes sensing single-photon avalanche diodes and a shielded single-photon avalanche diode; and
processing circuitry that is coupled to the shielded single-photon avalanche diode, wherein the processing circuitry is configured to update a bias voltage for the sensing single-photon avalanche diodes based on feedback from the shielded single-photon avalanche diode and wherein the processing circuitry comprises a comparator that identifies when an avalanche occurs in the shielded single-photon avalanche diode.
5. The system defined in claim 4 , wherein the processing circuitry comprises a counter that receives an output from the comparator and counts a number of avalanches in the shielded single-photon avalanche diode.
6. The system defined in claim 5 , wherein the processing circuitry is configured to:
determine a difference between the number of avalanches in the shielded single-photon avalanche diode from the counter and a target number of avalanches in the shielded single-photon avalanche diode; and
update the bias voltage for the sensing single-photon avalanche diodes based on the difference.
7. The system defined in claim 1 , wherein the processing circuitry is configured to update the bias voltage for the sensing single-photon avalanche diodes based on feedback from the shielded single-photon avalanche diode regarding a single parameter.
8. The system defined in claim 1 , wherein the processing circuitry is configured to update the bias voltage for the sensing single-photon avalanche diodes based on feedback from the shielded single-photon avalanche diode regarding multiple parameters.
9. The system defined in claim 1 , wherein the processing circuitry is configured to update the bias voltage for the sensing single-photon avalanche diodes based on feedback regarding a breakdown voltage.
10. A system, comprising:
a semiconductor device that includes at least one sensing single-photon avalanche diode and at least one dark single-photon avalanche diode;
a first measurement unit that is coupled to the at least one dark single-photon avalanche diode and that is configured to measure a first parameter for the at least one dark single-photon avalanche diode;
a second measurement unit that is coupled to the at least one dark single-photon avalanche diode and that is configured to measure a second parameter for the at least one dark single-photon avalanche diode; and
processing circuitry that is configured to:
determine an optimal bias voltage for the semiconductor device based on the measured first parameter and the measured second parameter; and
adjust a bias voltage for the semiconductor device to the determined optimal bias voltage.
11. The system defined in claim 10 , wherein the first and second parameters comprise parameters selected from the group consisting of: dark count rate, breakdown voltage, and quench resistance.
12. The system defined in claim 10 , wherein the first parameter is dark count rate and wherein the second parameters comprise a parameter selected from the group consisting of: breakdown voltage and quench resistance.