A high-speed impedance controlled output driver using pre-drive control for standard CMOS technology

Abstract

This paper describes a high-speed output driver circuit architecture that incorporates impedance control to allow matching the impedance of the output driver to the impedance of a printed circuit board trace. The impedance is set via an external resistor. Unlike many existing impedance controlled output drivers, the output impedance is not controlled by varying the number of output fingers included in the output, but instead by varying the pre-drive signals provided to the output stage. The impedance of the output as the output switches is examined and the signal integrity of the output driving a typical transmission line is presented.