Light receiving element and ranging system
The present technology relates to a light receiving element and a ranging system capable of improving a pixel characteristic by responding to a change in a breakdown voltage due to a temperature change. The light receiving element includes: a pixel array in which a plurality of pixels each including an SPAD is arranged in a matrix; a pixel drive unit that controls each pixel is the pixel array to be an active pixel or an inactive pixel; a leakage current detection unit that detects a leakage current of the inactive pixel; and a voltage control unit that controls a voltage supplied to a side of an anode or a side of a cathode of the SPAD such that the leakage current has a current value within a predetermined range. The present technology can be applied to, for example, a ranging system or the like that detects a distance to a subject in a depth direction.
1. A light receiving element comprising:
a pixel array in which a plurality of pixels each including an SPAD arranged in a matrix;
a pixel drive unit that controls each pixel in the pixel array to be an active pixel or an inactive pixel;
a leakage current detection unit that detects a leakage current of the inactive pixel; and
a voltage control unit that controls a voltage supplied to a side of an anode or a side of a cathode of the SPAD such that the leakage current has a current value within a predetermined range.
2. The light receiving element according to claim 1 , wherein
the pixel further comprises:
the SPAD;
a resistive component that is connected in series with the SPAD;
an output unit that outputs a detection signal indicating incidence of a photon on the SPAD; and
a switch that is turned on or off according to the control of the active pixel or the inactive pixel.
3. The light receiving element according to claim 1 , wherein
the pixel further comprises a switch that is turned on or off according to the control of the active pixel or the inactive pixel,
the leakage current detection unit includes a resistor that is connected to the switch, and
the voltage control unit controls the voltage supplied to the side of the anode of the SPAD.
4. The light receiving element according to claim 3 , wherein
the voltage control unit includes an operational amplifier that receives the leakage current as one input, and
the operational amplifier controls the voltage supplied to the side of the anode of the SPAD.
5. The light receiving element according to claim 3 , wherein
the voltage control unit includes a comparator that receives the leakage current as one input, and controls the voltage supplied to the side of the anode of the SPAD depending on output of the comparator.
6. The light receiving element according to claim 1 , wherein
the leakage current detection unit is connected to the side of the anode of the SPAD, and
the voltage control unit controls the voltage supplied to the side of the anode of the SPAD.
7. The light receiving element according to claim 6 , wherein
the leakage current detection unit includes a transistor.
8. The light receiving element according to claim 6 , wherein
the pixel further comprises a switch that is turned on or off according to the control of the active pixel or the inactive pixel, and
the switch connects the anode of the SPAD to ground when turned on.
9. The light receiving element according to claim 1 , wherein
the pixel further comprises a switch that is turned on or off according to the control of the active pixel or the inactive pixel,
the leakage current detection unit includes a resistor that is connected to the switch, and
the voltage control unit controls the voltage supplied to the side of the cathode of the SPAD.
10. The light receiving element according to claim 9 , wherein
the voltage control unit includes an operational amplifier that receives the leakage current as one input, and
the operational amplifier controls the voltage supplied to the side of the cathode of the SPAD.
11. A ranging system comprising:
a lighting device that emits emitted light; and
a light receiving element that receives reflected light of the emitted light, wherein
the light receiving element comprises:
a pixel array in which a plurality of pixels each including an SPAD is arranged in a matrix;
a pixel drive unit that controls each pixel in the pixel array to be an active pixel or an inactive pixel;
a leakage current detection unit that detects a leakage current of the inactive pixel; and
a voltage control unit that controls a voltage supplied to a side of an anode or a side of a cathode of the SPAD such that the leakage current has a current value within a predetermined range.