Analytic models of CMOS logic in various regimes

Abstract

In this paper, comparative analytic models of static and dynamic characteristics of CMOS digital circuits in strong, weak and mixed inversion regime have been described. Term mixed inversion is defined for the first time. The paper shows that there is an analogy in behavior and functional dependencies of parameters in all three CMOS regimes. Comparative characteristics of power consumption and speed in static regimes are given. Dependency of threshold voltage and logic delay time on temperature has been analyzed. Dynamic model with constant current is proposed. It is shown that digital circuits with dynamic threshold voltage of MOS transistor (DT-CMOS) have better logic delay characteristics. The analysis is based on simplified current-voltage MOS transistor models in strong and weak inversion regimes, as well as PSPICE software using 180 nm technology parameters.

Keywords

• CMOS digital circuits
• weak inversion
• strong inversion