A differential signal generating device includes a control circuit and a differential signal driver receiving a single-ended signal. The control circuit receives a source signal and generates a control signal corresponding to a first mode when the source signal conforms with a first pre-defined state, and corresponding to a second mode when the source signal conforms with a second pre-defined state. Variations of the source signal are related to signal content of the single-ended signal. The differential signal driver is coupled to the control unit for receiving the control signal therefrom. The differential signal driver outputs a differential signal output according to the single-ended signal when the control signal corresponds to the first mode. The differential signal driver outputs a non-differential signal output when the control signal corresponds to the second mode.