Patent ID: 7847576

Claim:
A comparator with a latching function that receives a pair of differential signals consisting of a positive differential signal and a negative differential signal, and that determines an amplitude level of the pair of differential signals at a predetermined timing and latches a signal indicating a determination result, the comparator comprising: a positive input terminal to which the positive differential signal is inputted; a negative input terminal to which the negative differential signal is inputted; a first fixed voltage terminal to which a first fixed voltage is supplied; a second fixed voltage terminal to which a second fixed voltage is supplied; a positive line in which the positive differential signal is propagated; a negative line in which the negative differential signal is propagated; and a comparison amplification unit that compares a level of a signal in the positive line with that of the signal in the negative line and latches a comparison result, wherein the comparison amplification unit includes: a first inverter, an input terminal of which is connected to the positive line, an output terminal of which is connected to the negative line, and a power supply terminal on one side of which is connected to the first fixed voltage terminal; a second inverter, an input terminal of which is connected to the negative line, an output terminal of which is connected to the positive line, and a power supply terminal on one side of which is connected to the first fixed voltage terminal; and a first activation switch that can selectively switch between a state where the first activation switch outputs the first fixed voltage to the other power supply terminals of the first and second inverters that are connected in common, such that the comparison amplification unit is inactivated, and a state where the first activation switch outputs the second fixed voltage such that the comparison amplification unit is activated, and wherein the comparison amplification unit outputs a signal corresponding to at least one of the signal in the positive line and the signal in the negative line at a timing after the comparison amplification unit is activated.