US Patent 7164299 Output buffer circuit having pre-emphasis function

An output buffer circuit having a so-called pre-emphasis function of emphasizing a signal waveform in data transmission in an information processing device or the like according to an attenuation of a transmission line, includes a first buffer which receives input of an input signal which gives a logical value of a signal to drive the transmission line and a second buffer which drives the transmission line in cooperation with the first buffer, thereby cutting off, at the time of de-pre-emphasis when the pre-emphasis function is disabled, current flowing through the second buffer.