Terminal-oriented model for merged transistor logic (MTL)

A simple device model is derived to represent merged transistor logic (MTL) circuit behavior. Using the Ebers-Moll equations, the proper definitions of the various current gains are derived, and it is shown that MTL devices can be basically interpreted as n-p-n transistors having an additional base current source. The relations between the intensity of this source and the current actually supplied are derived. Time behavior is modeled according to the charge control concept. Using this model, circuit delays are given as a function of current gains, collector and emitter time constants, supply current, and of fan-out.