The present invention discloses a signal interface to transmit a data signal to a driving circuit. The signal interface comprises a first circuit, a second circuit and a data bus. The first circuit comprises a first register. The second circuit comprises a selector, a second register, a receiver and a third register. If the data signal is a single-end signal, the first register and the selector receive the data signal. Then, the selector transmits the data signal to the second register. The data bus transmits the signal saved in the first register and the second register to the driving circuit. If the data signal is a serial signal, the selector receives and transmits the data signal to the receiver to have it transferred to a single-end signal. Then, the signal is transmitted to the third register and output via the data bus.