Patent ID: 8823575

Claim:
An AD conversion circuit comprising: a reference signal generation unit configured to generate a reference signal increasing or decreasing with passage of time; a comparison unit that includes a first comparison circuit and a second comparison circuit, each of which compares an analog signal to be subjected to an AD conversion with the reference signal; a clock generation unit that includes a delay circuit in which a plurality of delay units are connected to one another, the clock generation unit outputting a first lower phase signal and a second lower phase signal based on clock signals that are output from each of the plurality of delay units; a latch unit that includes a first latch circuit and a second latch circuit, the first latch circuit being configured to latch a logical state of the first lower phase signal that is output from the clock generation unit, the second latch circuit being configured to latch a logical state of the second lower phase signal that is output from the clock generation unit; and a counting unit configured to perform counting based on the second lower phase signal that is output from the clock generation unit, wherein the first comparison circuit is configured to complete a first comparison process at a first timing at which the reference signal satisfies a predetermined condition with respect to the analog signal, the second comparison circuit is configured to determine a second timing corresponding to a magnitude of the analog signal, the first timing is later than the second timing, the latch unit is configured to make the second latch circuit, to which the second lower phase signal is input, valid, and then make the first latch circuit, to which the first lower phase signal is input, valid at a timing according to the second timing, and the latch unit is configured to latch the first lower phase signal through the first latch circuit and the second lower phase signal through the second latch circuit at a timing according to the first timing.