Digitally adjustable resistors in CMOS for high-performance applications

摘要

Methods by which CMOS circuits can be adjusted digitally to generate controlled impedances for use in high-performance circuits are described. Since digital signals are the only inputs to these circuits, on-chip DC power dissipation can be reduced, the circuit can be made more robust, and the impedance of the circuit can be adjusted by manipulating the input digital information. A design of a CMOS series terminated line driver is discussed, and the utilization of the controlled impedance in terminating transmission lines on-chip, constant delay lines, and controlled di/dt output buffers is discussed.