Imaging apparatus and imaging system
This technology relates to an imaging apparatus and an imaging system for improving the accuracy of distance measurement performed by use of SPADs. The imaging apparatus includes a pixel array section having pixel sections arrayed therein. Each pixel section includes: an SPAD (single photon avalanche photodiode); a resistance component configured to be connected serially with the SPAD; an output section configured to output a light reception signal indicating photon incidence on the SPAD; and a pulse generation section configured to output a pulse signal in synchronism with the output of the light reception signal. Each pixel sections further includes at least one of: a switch configured to be connected interposingly between the SPAD and the resistance component and turned off in synchronism with the pulse signal; or a pull-in section configured to pull in an input current flowing through the SPAD via the resistance component in synchronism with the pulse signal, thereby suppressing the input current flowing through the SPAD. This technology may be applied to cameras that capture range images, for example.
1. A light detecting device comprising:
an avalanche photodiode having a first terminal and a second terminal, the first terminal of the avalanche photodiode being coupled to a first potential;
a current source configured to supply a current from a second potential to the avalanche photodiode and to perform passive quenching;
an output circuit coupled to the second terminal of the avalanche photodiode and configured to output a light reception signal;
a pulse generation circuit configured to output a pulse signal based on the light reception signal;
a transistor disposed between the second terminal and a third potential; and
a switch configured to selectively limit the current based on the pulse signal,
wherein an output of the pulse generation circuit is coupled to both a gate of the transistor and the switch, wherein the avalanche photodiode, the switch, and the current source are directly connected in series between the first potential and the second potential, and wherein the switch is interposed between the second terminal of the avalanche photodiode and the current source.
2. The light detecting device according to claim 1 , wherein the transistor pulls in an input current flowing through the avalanche photodiode when the pulse signal is input and does not pull in the input current when the pulse signal is not input.
3. The light detecting device according to claim 1 , wherein the pulse generation circuit outputs the pulse signal upon detection of the light reception signal, wherein the pulse signal is output with a predetermined width.
4. The light detecting device according to claim 1 , wherein the current source includes a transistor.
5. The light detecting device according to claim 1 , wherein the output circuit outputs the light reception signal on a basis of a potential of the second terminal of the avalanche photodiode.
6. The light detecting device according to claim 1 , wherein the switch is coupled in series with the avalanche photodiode and the current source.
7. The light detecting device according to claim 1 , wherein the switch comprises a transistor.
8. The light detecting device according to claim 1 , wherein the second terminal comprises a cathode of the avalanche photodiode.
9. The light detecting device according to claim 1 , wherein the output circuit includes at least one inverter.
10. The light detecting device according to claim 1 , wherein a first switch terminal of the switch is connected to the current source and a second switch terminal of the switch is connected to the second terminal of the avalanche photodiode.
11. A light detecting system, comprising:
a lighting apparatus configured to emit irradiation light; and
a light detecting apparatus configured to receive reflected light;
wherein the light detecting apparatus includes
an avalanche photodiode having a first terminal and a second terminal, the first terminal of the avalanche photodiode being coupled to a first potential;
a current source configured to supply a current from a second potential to the avalanche photodiode and to perform passive quenching;
an output circuit coupled to the second terminal of the avalanche photodiode and configured to output a light reception signal;
a pulse generation circuit configured to output a pulse signal based on the light reception signal;
a transistor disposed between the second terminal and a third potential; and
a switch configured to selectively limit the current based on the pulse signal,
wherein an output of the pulse generation circuit is coupled to both a gate of the transistor and the switch, wherein the avalanche photodiode, the switch, and the current source are directly connected in series between the first potential and the second potential, and wherein the switch is interposed between the second terminal of the avalanche photodiode and the current source.
12. A light detecting device comprising:
an avalanche photodiode having a first terminal and a second terminal, the first terminal of the avalanche photodiode being coupled to a first potential;
a current source configured to supply a current from a second potential to the avalanche photodiode and to quenching;
an output circuit coupled to the second terminal of the avalanche photodiode and configured to output a light reception signal;
a pulse generation circuit configured to output a pulse signal based on the light reception signal;
a transistor disposed between the second terminal and a third potential; and
a switch configured to selectively limit the current based on the pulse signal,
wherein an output of the pulse generation circuit is coupled to both a gate of the transistor and the switch, wherein the avalanche photodiode, the switch, and the current source are directly connected in series between the first potential and the second potential, and wherein the switch is turned off when the pulse signal is input and is turned on when the pulse signal is not input.