Low power CMOS off-chip drivers with slew-rate difference

Abstract

This paper proposes an approach to reduce the short circuit current of CMOS off-chip drivers by individually controlling the input slew rates to the P and N channel transistors that drive the output pad. The slew rates are deliberately designed such that the N(P) transistor at the output stage will be turned off faster than the P(N) transistor is turned on for low-to-high (high-to-low) output transitions. It is demonstrated experimentally by HSPICE simulation that the off-chip driver designed by the proposed approach not only produces viable power-delay products, but also results in smaller noise.