Light receiving element and ranging system
A light receiving element and a ranging system is provided which achieve improvement of pixel characteristics while allowing variation in a breakdown voltage of an SPAD. The light receiving element includes a pixel array in which a plurality of pixels is arranged in a matrix, and a pixel driving unit configured to control respective pixels of the pixel array to be active pixels or non-active pixels. The pixel includes an SPAD, a transistor connected to the SPAD in series, an inverter configured to output a detection signal indicating incidence of a photon on the SPAD, a first transistor which is switched on or off in accordance with control of the pixels to be the active pixels or the non-active pixels, and a second transistor connected to the first transistor in series.
1. A light receiving element, comprising:
a pixel array in which a plurality of pixels is arranged in a matrix; and
a pixel driving unit configured to control respective pixels of the pixel array to be active pixels or non-active pixels,
wherein the pixel includes:
a single photon avalanche diode (SPAD);
a resistance component connected to the SPAD in series;
an output unit configured to output a detection signal indicating incidence of a photon on the SPAD;
a first transistor which is switched on or off in accordance with control of the pixels to be the active pixels or the non-active pixels; and
a second transistor connected to the first transistor in series,
wherein the second transistor is a diode-connected transistor.
2. The light receiving element according to claim 1 ,
wherein the second transistor is connected to a body diode of the first transistor in parallel.
3. The light receiving element according to claim 2 ,
wherein a current flowing direction in the second transistor is opposite to a current flowing direction in the body diode.
4. A light receiving element, comprising:
a pixel array in which a plurality of pixels is arranged in a matrix; and
a pixel driving unit configured to control respective pixels of the pixel array to be active pixels or non-active pixels,
wherein the pixel includes:
a single photon avalanche diode (SPAD);
a resistance component connected to the SPAD in series;
an output unit configured to output a detection signal indicating incidence of a photon on the SPAD;
a first transistor which is switched on or off in accordance with control of the pixels to be the active pixels or the non-active pixels; and
a second transistor connected to the first transistor in series,
wherein the output unit includes a CMOS inverter, and
a threshold voltage of the second transistor is lower than a threshold voltage of the CMOS inverter.
5. A ranging system, comprising:
an illumination apparatus configured to radiate irradiation light; and
a light receiving element configured to receive reflected light of the irradiation light,
wherein the light receiving element includes:
a pixel array in which a plurality of pixels is arranged in a matrix; and
a pixel driving unit configured to control respective pixels of the pixel array to be active pixels or non-active pixels, and
the pixel includes:
a single photon avalanche diode (SPAD);
a resistance component connected to the SPAD in series;
an output unit configured to output a detection signal indicating incidence of a photon on the SPAD;
a first transistor which is switched on or off in accordance with control of the pixels to be the active pixels or the non-active pixels; and
a second transistor connected to the first transistor in series,
wherein the second transistor is a diode-connected transistor.