Non-Volatile Pass Transistor Logic
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
For transistor circuits for operations in which part of the operand set is relatively fixed, such logic being sometimes known as 'pass transistor logic', non-volatile FET devices can be used for the pass elements that represent that part of the operand set. Fig. 1 illustrates such an exclusive-OR using two pass transistors for A and A. To assure that no signal levels are reduced from source to drain, the gate voltages, i.e., A and A,are at least one threshold level (1 V) more positive than B and B signals. Hence, if the output is to be used as a gate input, it must first pass through a level converter. On the other hand, if the logic is structured so that the output goes to a source, there is significant power, performance and density advantage. Limitations may arise from the build-up of series RC time constants.