Photodetection device and photodetection system
A photodetection device according to the present disclosure includes a plurality of light-receiving sections that each generates a pulse signal including a pulse corresponding to a result of light reception, a plurality of edge detectors that each generates a detection signal by detecting an edge of the pulse in the pulse signal generated by a corresponding light-receiving section, and an adder that generates a detection value indicating number of the pulses on the basis of a plurality of the detection signals. The edge detectors each include a first latch circuit that generates a first signal by latching the pulse signal on the basis of a first clock signal, a second latch circuit that generates a second signal by latching the first signal on the basis of a second clock signal that is an inverted signal of the first clock signal, a combination circuit that generates a third signal on the basis of the pulse signal, the first signal, and the second signal, and a third latch circuit that generates the detection signal by latching the third signal on the basis of the first clock signal.
1 . A photodetection device comprising:
a plurality of light-receiving sections that each includes a light-receiving element, and generates a pulse signal including a pulse corresponding to a result of light reception by the light-receiving element;
a plurality of edge detectors each of which is provided for a corresponding one of the plurality of light-receiving sections, and generates a detection signal by detecting an edge of the pulse in the pulse signal generated by the corresponding one of the plurality of light-receiving sections; and
an adder that generates a detection value indicating number of the pulses by performing addition processing on a basis of a plurality of the detection signals generated by the plurality of edge detectors, wherein
each of the plurality of edge detectors includes
a first latch circuit that generates a first signal by latching the pulse signal on a basis of a first clock signal,
a second latch circuit that generates a second signal by latching the first signal on a basis of a second clock signal that is an inverted signal of the first clock signal,
a combination circuit that generates a third signal on a basis of the pulse signal, the first signal, and the second signal, and
a third latch circuit that generates the detection signal by latching the third signal on a basis of the first clock signal.
2 . The photodetection device according to claim 1 , wherein
each of the plurality of edge detectors detects an edge of the pulse in a detection period based on the first clock signal and the second clock signal, and
a pulse width of the pulse is equal to or larger than a time width of the detection period.
3 . The photodetection device according to claim 2 , wherein a time length of the detection period is a time length corresponding to a period of the first clock signal.
4 . The photodetection device according to claim 1 , further comprising a cumulative adder that generates an accumulated value by performing cumulative addition processing on a basis of the detection value.
5 . The photodetection device according to claim 4 , further comprising a counter that performs count processing, wherein
the cumulative adder sets a flag active every time the accumulated value reaches a predetermined value, and
the counter performs the count processing on a basis of the flag.
6 . The photodetection device according to claim 1 , wherein
a plurality of the light-receiving elements is provided on a first semiconductor substrate, and
the plurality of edge detectors is provided on a second semiconductor substrate bonded to the first semiconductor substrate.
7 . A photodetection device comprising:
a plurality of light-receiving sections that each includes a light-receiving element, and generates a pulse signal including a pulse corresponding to a result of light reception by the light-receiving element;
a plurality of edge detectors each of which is provided for a corresponding one of the plurality of light-receiving sections, and generates a first detection signal and a second detection signal by detecting an edge of the pulse in the pulse signal generated by the corresponding one of the plurality of light-receiving sections;
a first adder that generates a first detection value indicating number of the pulses by performing addition processing on a basis of a plurality of the first detection signals generated by the plurality of edge detectors; and
a second adder that generates a second detection value indicating number of the pulses by performing addition processing on a basis of a plurality of the second detection signals generated by the plurality of edge detectors, wherein
each of the plurality of edge detectors includes
a first latch circuit that generates a first signal by latching the pulse signal on a basis of a first clock signal,
a second latch circuit that generates a second signal by latching the pulse signal on a basis of a second clock signal,
a first combination circuit that generates a third signal on a basis of the pulse signal and the first signal, and
a second combination circuit that generates a fourth signal on a basis of the pulse signal and the second signal, and
each of the plurality of edge detectors generates the first detection signal on a basis of the third signal, and generates the second detection signal on a basis of the fourth signal.
8 . The photodetection device according to claim 7 , wherein
each of the plurality of edge detectors further includes
a third latch circuit that generates the first detection signal by latching the third signal on a basis of a third clock signal that is an inverted signal of the first clock signal, and
a fourth latch circuit that generates the second detection signal by latching the fourth signal on a basis of a fourth clock signal that is an inverted signal of the second clock signal.
9 . The photodetection device according to claim 7 , wherein the second clock signal is an inverted signal of the first clock signal.
10 . The photodetection device according to claim 7 , wherein a phase of the second clock signal is different from a phase of the first clock signal.
11 . The photodetection device according to claim 7 , wherein
each of the plurality of edge detectors detects an edge of the pulse in a detection period based on the first clock signal and the second clock signal, and
a pulse width of the pulse is equal to or larger than a time width of the detection period.
12 . The photodetection device according to claim 11 , wherein
the first clock signal changes between a first level and a second level, and
a time length of the detection period is a time length of a period in which the first clock signal maintains the first level.
13 . The photodetection device according to claim 7 , further comprising a cumulative adder that generates an accumulated value by performing cumulative addition processing on a basis of the first detection value.
14 . The photodetection device according to claim 13 , further comprising a counter that performs count processing, wherein
the cumulative adder sets a flag active every time the accumulated value reaches a predetermined value, and
the counter performs the count processing on a basis of the flag.
15 . The photodetection device according to claim 13 , wherein
the first detection value includes a third detection value and a fourth detection value, and
the cumulative adder generates a first accumulated value by performing the cumulative addition processing on a basis of the third detection value, and generates a second accumulated value by performing the cumulative addition processing on a basis of the fourth detection value.
16 . The photodetection device according to claim 15 , further comprising a first counter and a second counter that perform count processing, wherein
the cumulative adder sets a first flag active every time the first accumulated value reaches a predetermined value, and sets a second flag active every time the second accumulated value reaches the predetermined value,
the first counter performs the count processing on a basis of the first flag, and
the second counter performs the count processing on a basis of the second flag.
17 . The photodetection device according to claim 7 , wherein
a plurality of the light-receiving elements is provided on a first semiconductor substrate, and
the plurality of edge detectors is provided on a second semiconductor substrate bonded to the first semiconductor substrate.
18 . A photodetection system comprising:
a light-emitting section that emits light; and
a photodetector that detects light reflected by a detection object of the light emitted from the light-emitting section, wherein
the photodetector includes
a plurality of light-receiving sections that each includes a light-receiving element, and generates a pulse signal including a pulse corresponding to a result of light reception by the light-receiving element,
a plurality of edge detectors each of which is provided for a corresponding one of the plurality of light-receiving sections, and generates a detection signal by detecting an edge of the pulse in the pulse signal generated by the corresponding one of the plurality of light-receiving sections, and
an adder that generates a detection value indicating number of the pulses by performing addition processing on a basis of a plurality of the detection signals generated by the plurality of edge detectors, and
each of the plurality of edge detectors includes
a first latch circuit that generates a first signal by latching the pulse signal on a basis of a first clock signal,
a second latch circuit that generates a second signal by latching the first signal on a basis of a second clock signal that is an inverted signal of the first clock signal,
a combination circuit that generates a third signal on a basis of the pulse signal, the first signal, and the second signal, and
a third latch circuit that generates the detection signal by latching the third signal on a basis of the first clock signal.
19 . A photodetection system comprising:
a light-emitting section that emits light; and
a photodetector that detects light reflected by a detection object of the light emitted from the light-emitting section, wherein
the photodetector includes
a plurality of light-receiving sections that each includes a light-receiving element, and generates a pulse signal including a pulse corresponding to a result of light reception by the light-receiving element,
a plurality of edge detectors each of which is provided for a corresponding one of the plurality of light-receiving sections, and generates a first detection signal and a second detection signal by detecting an edge of the pulse in the pulse signal generated by the corresponding one of the plurality of light-receiving sections,
a first adder that generates a first detection value indicating number of the pulses by performing addition processing on a basis of a plurality of the first detection signals generated by the plurality of edge detectors, and
a second adder that generates a second detection value indicating number of the pulses by performing addition processing on a basis of a plurality of the second detection signals generated by the plurality of edge detectors,
each of the plurality of edge detectors includes
a fourth latch circuit that generates a first signal by latching the pulse signal on a basis of a first clock signal,
a second latch circuit that generates a second signal by latching the pulse signal on a basis of a second clock signal,
a first combination circuit that generates a third signal on a basis of the pulse signal and the first signal, and
a second combination circuit that generates a fourth signal on a basis of the pulse signal and the second signal, and
each of the plurality of edge detectors generates the first detection signal on a basis of the third signal, and generates the second detection signal on a basis of the fourth signal.