A comparator includes an input pair circuit, an isolation circuit, and a latch circuit. The input pair circuit receives first and second input signals to generate first and second signals. The isolation circuit is selectively turned on according to a clock signal to transmit the first signal from the input pair circuit to a first output node and transmit the second signal from the input pair circuit to a second output node. The latch circuit adjusts a level of the first output node to generate a first output signal, adjusts a level of the second output node to generate a second output signal, and selectively resets the levels of the first and the second output nodes according to the clock signal. When the latch circuit resets the levels of the first and the second output nodes, the isolation circuit is not turned on.