TABLE OF CONTENTS This chapter introduces a completely different application for the FGMOS transistors, in digital circuit design. The device can be used to implement digital functions in a much more compact way, which results in the desired reduction of power. The methodology followed for this consists of the following steps: 1. Design the digital functions at the system level using threshold gates. 2. Design the corresponding threshold gates at the circuit level using FGMOS transistors. 3. Design the whole system at the circuit level using the threshold gates developed in 2.
Threshold Gates are digital circuits whose functionality is based on the so called majorityor threshold decision principle. The threshold decision principle states that the value of the signal at the circuit output depends on whether the arithmetic sum of values at the inputs exceeds or falls below a threshold value. This general definition includes as special cases conventional logic gates, such as AND and OR.
For manyyears, logic circuit design based on threshold gates has been considered as an alternative to the traditional logic gate design procedure. The threshold gate intrinsically implements a complex function. If, instead of using standard logic gates, the threshold gate is used as main block of the system, the number of gates as well as the gate levels can be reduced. However, the growing interest in threshold logic is mainlydue to the recent theoretical results that show how bounded level networks of threshold gates can implement functions that would require unbounded level networks of...
