A Theory of Constant Et^2 CMOS Circuits

Abstract

CMOS pulldown networks are characterized by their switching energy (E) and propagation delay (t), and voltage scaling has been shown to allow E or t to be adjusted, while Et^2 remains constant. Previously, this argument about single pulldown stages was applied to arbitrary digital circuits by assuming that the total delay of any such circuit was a sum of single pulldown and pullup stage delays, neglecting the time variation of the input to each stage. In this paper, the statement that Et^2 is independent of voltage scaling is generalized to arbitrary networks of CMOS transitors using only a weaker assumption: that every node has a capacitance.