Patent ID: 6297677
Filing Date: 2001-10-02
Classification: H03K

Abstract:
A method for providing control of a slew rate of a driver, the driver capable of launching signals at a driving end of a transmission line and of terminating signals at a receiver end of the transmission line, the driver having an output voltage and an impedance control system, the driver coupled to the transmission line and the driver coupled to a first supply voltage, the method controlling the slew rate of the driver across process, voltage, and temperature (PVT) variations, the method comprising:establishing a RC time constant for a voltage transition of a number of output elements, the number of output elements controlling a launching of a signal;controlling the RC time constant associated with the number of output elements across a plurality of PVT variations by adjusting the number of output elements controlling the launching of the signal;providing the circuit with a pull up circuit, the pull up circuit receiving an input signal and providing an output signal, the pull up circuit including the first subset of the number of output elements; andproviding the circuit with a pull down circuit having an impedance, the pull down circuit receiving the input signal and the pull down circuit including the second subset of the number of output elements.