Photoelectric conversion device, method of driving photoelectric conversion device, imaging system, and moving body
A photoelectric conversion device includes an avalanche multiplying photodiode, a signal generation unit that includes a control unit configured to control an applied voltage to the photodiode and generates a photon detection pulse based on an output generated by incidence of a photon to the photodiode, and a counter that counts the photon detection pulse output from the signal generation unit, and the counter outputs a setting value detection signal when a count value of the photon detection pulse reaches a predetermined setting value, and in response to receiving the setting value detection signal, the control unit controls the applied voltage to the photodiode so as to stop generation of an avalanche current in the photodiode.
1. A photoelectric conversion device comprising:
an avalanche multiplying photodiode;
a transistor configured to control an applied voltage to a cathode terminal of the photodiode;
a signal generation unit that generates a photon detection pulse based on an avalanche current generated by incidence of a photon to the photodiode;
a counter configured to count the photon detection pulse output from the signal generation unit; and
a control unit configured to stop generation of the avalanche current at the avalanche multiplying photodiode by controlling a voltage applied to a gate of the transistor in response to a count value of the photon detection pulse reaching a predetermined setting value.
2. The photoelectric conversion device according to claim 1 , wherein the counter outputs a setting value detection signal to the control unit when the count value of the photon detection pulse reaches the predetermined setting value.
3. The photoelectric conversion device according to claim 2 , wherein the control unit is configured to control the applied voltage to the gate of the transistor so as to stop generation of the avalanche current in the photodiode in response to receiving the setting value detection signal.
4. The photoelectric conversion device according to claim 2 , wherein the control unit includes the transistor provided between a power supply node and the photodiode and is configured to stop supplying of the applied voltage to the avalanche multiplying photodiode from the power supply node by turning off the transistor in response to receiving the setting value detection signal.
5. The photoelectric conversion device according to claim 3 , wherein the control unit includes the transistor provided between a power supply node and the photodiode and is configured to stop supplying of the applied voltage to the avalanche multiplying photodiode from the power supply node by turning off the transistor in response to receiving the setting value detection signal.
6. The photoelectric conversion device according to claim 4 , wherein the control unit further includes a MOS transistor that is serially connected to the transistor and provided between the power supply node and the photodiode and is controlled in response to a change in a voltage of the cathode terminal of the photodiode due to incident of a photon to the photodiode.
7. The photoelectric conversion device according to claim 5 , wherein the control unit further includes a MOS transistor that is serially connected to the transistor and provided between the power supply node and the photodiode and is controlled in response to a change in a voltage of the cathode terminal of the photodiode due to incident of a photon to the photodiode.
8. The photoelectric conversion device according to claim 4 , wherein the transistor is controlled by the setting value detection signal.
9. The photoelectric conversion device according to claim 5 , wherein the transistor is controlled by the setting value detection signal.
10. The photoelectric conversion device according to claim 1 further comprising a pixel region in which a plurality of pixels each including the photodiode, the transistor, the signal generation unit, the control unit, and the counter is arranged over a plurality of rows and a plurality of columns.
11. An imaging system comprising:
the photoelectric conversion device according to claim 1 , and
a signal processing unit configured to process a signal output from the photoelectric conversion device.
12. A moving body comprising:
the photoelectric conversion device according to claim 1 ;
a distance information acquisition device that acquires distance information on a distance to an object, based on a signal from the photoelectric conversion device; and
a control device that controls the moving body based on the distance information.
13. The photoelectric conversion device according to claim 1 , wherein the transistor also functions as a quench circuit for the photodiode.
14. The photoelectric conversion device according to claim 2 ,
wherein an anode terminal of the photodiode is connected to a first power supply voltage, and
wherein the cathode terminal of the photodiode is connected to a second power supply voltage.
15. The photoelectric conversion device according to claim 14 ,
wherein the control unit is connected to a third power supply voltage and a fourth power supply voltage lower than the third power supply voltage, and
wherein the control unit is configured to output the third power supply voltage to the gate of the transistor if the control unit receives the setting value detection signal, and to output the fourth power supply voltage to the gate of the transistor if the control unit does not receive the setting value detection signal.
16. The photoelectric conversion device according to claim 15 , wherein the second power supply voltage and the third power supply voltage are the same voltage.