Photodetection device and counter circuit

Abstract

An increase in the number of state transitions at a time of counting is suppressed. In one example, a photodetection device includes light receiving units that respectively output pulses generated in accordance with incidence of photons. A counter circuit counts the pulses from a respective light receiving unit. The counter circuit includes 2-bit Johnson counters whose states transition on a basis of a transition input. A second bit of a count output of a 2-bit Johnson counter at a preceding stage is used as the transition input of a 2-bit Johnson counter at a subsequent stage. The 2-bit Johnson counters may each include flip-flops connected in two stages, and in each of the plurality of 2-bit Johnson counters, an inverted value of an output of a flip-flop at a subsequent stage may be used as an input of a flip-flop at a preceding stage.

Dependencies are inferred from the claim text.