An empirical and analytical comparison of delay elements and a new delay element design

This paper comprehensively reviews five different delay element architectures for use in CMOS VLSI design. The first four delay elements that we analyze are already in general use; they are the transmission gate, cascaded inverters, thyristor, and voltage-controlled delay element. The fifth delay element, a transmission gate with Schmitt trigger, is a new architecture that we are proposing in this paper. We compare these delay elements, both analytically and through simulations, in terms of four important parameters: delay, signal integrity, power consumption, and area, and find that they have widely varying characteristics. Depending upon the delay value required in an application, results presented in this paper will enable a designer to select the most appropriate delay element that meets signal integrity, power consumption, and area specifications.