A detecting circuit includes: a first offset generating circuit, arranged to apply a first offset to an input signal pair and accordingly generate a first output signal pair; and a first sampling circuit, coupled to the first offset generating circuit, the first sampling circuit arranged to sample the first output signal pair to generate a first sampling signal, wherein the first sampling signal is utilized to identify a data signal on the input signal pair, and the first sampling circuit is controlled by a first signal that is irrelevant to the input signal pair.