Transmission Gate Modeling in an Existing Three-Value Simulator

Existing three value (0, 1, X,) logic simulators cannot support the use of MOS transmission gates, but this deficiency can be easily eliminated by the addition of one logic value - the high impedance (Z) state. This paper demonstrates that complete transmission gate modeling, including bi-directional operation and Ratio Logic, can be accomplished with this single Z state and explicit node models; and, since four states require the same internal storage as three states, such an enhancement would not require a major software rewrite.