A low power differential signaling transmitter includes a switchable current source apparatus and a differential signaling generator coupled to the switchable current source apparatus. The switchable current source apparatus receives a first input voltage and a second input voltage, and generates a plurality of reference currents according to the first input voltage and the second input voltage. The differential signaling generator includes a plurality of first transistors, a plurality of second transistors, a first output voltage terminal and a second output voltage terminal. The on or off states of the first transistors and the second transistors are controlled by the reference currents. The first output voltage terminal outputs a first output voltage, and the second output voltage terminal outputs a second output voltage. The first output voltage and the second output voltage are determined according to the on or off states of the first and second transistors.