Patent ID: 7498844

Claim:
An output driver, comprising: a pre-pull up drive unit configured to perform a pre-pull up drive operation; a pre-pull down drive unit configured to perform a pre-pull down drive operation; a drive unit configured to perform a drive operation in response to outputs of the pre-pull up drive unit and the pre-pull down drive unit; and a compensation unit configured to sense changes of driving strengths of the pre-pull up drive unit and the pre-pull down drive unit to control the drive operations of the pre-pull up drive unit and the pre-pull down drive unit, wherein the compensation unit includes: a slew rate sensing unit configured to sense changes of the slew rate of the drive unit according to surrounding conditions; a digitalization unit configured to digitalize an output of the slew rate sensing unit and to output the digitized output of the slew rate sensing unit; and a signal generation unit configured to generate a plurality of the slew rate compensation signals according to an output of the slew rate sensing unit, wherein the digitized output of the slew rate sensing unit is inputted to the signal generation unit, wherein the driving strengths of the pre-pull up drive unit and the pre-pull down drive unit are stabilized in response to slew rate compensation signals output from the compensation unit, wherein the pre-pull up drive unit comprises; a main pre-pull up drive unit configured to perform a main drive operation; and a supplementary pre-pull up drive unit configured to adjust the driving strength of the pre-pull up drive unit, wherein the pre-pull down drive unit comprises a main pre-pull down drive unit configured to perform the main drive operation; and a supplementary pre-pull down drive unit configured to adjust the driving strength of the pre-pull down drive unit, wherein the slew rate sensing unit comprises a MOS transistor; and the pre-pull up drive unit and the pre-pull down drive unit each comprise an MOS transistor.