PURPOSE: To transmit a signal between LSIs with low power consumption at high speed with less waveform distortion by constituting a driver circuit provided with an LSI signal output stage with a BiCMOS circuit and matching its output impedance with a characteristic impedance of a connected signal transmission line.

CONSTITUTION: A driver circuit 12 provided to a signal output stage of an LSI is constituted of a BiCMOS circuit and its output impedance is matched with the characteristic impedance of a signal transmission line 13 to be connected. Thus, no level conversion circuit is required for the input and output of the LSI, the high speed is attained and the power consumption is suppressed. Moreover, it is easy to match the output impedance, both at H and L sides with the characteristic impedance of the transmission line 13 and high speed signal transmission with less waveform distortion is attained.