Data driving circuit and semiconductor memory device having the same

Abstract

A data driving circuit includes a driver in which a driving current is controlled in response to predetermined bits of digital control signal and which receives a differential input data signal to generate differential output data signal; and a digital control signal generator for storing and generating the digital control signal. The driver includes a pre-driver for passing a pre driving current in response to a bias voltage and for receiving the differential input data signal(s) to generate first and second signals; and a main driver in which a main driving current is controlled in response to the digital control signal and which generates the differential output data signals in response to the first and second signals. The data driving circuit can not only vary an amplitude and a level but also shift a level, and by varying a current of the current sources in response to the digital control signal, a margin is secured in a saturation region of transistors which constitute the current sources, thereby generating a stable differential output data signals insensitive to a noise.