Mask-programmable multiple-valued logic gate using resonant tunnelling diodes

The design of a 1-input and a 2-input 4-valued logic gate is described. These gates can be used to implement cells of a gate array, with the benefit of having programmable functionality and multiple-valued logic input and output lines. Programmable functionality allows any of the four billion functions of a 2-input 4-valued logic gate to be implemented by the same cell, and multiple-valued logic signal lines can reduce the area needed to be reserved for intercell routing. A key component of these cells is the resonant tunnelling diode, an ultrafast and small quantum electronic device that can be used in conjunction HBTs to make compact literal circuits and decoders. So far as non-gate-array implementations are concerned, compactness can be improved further by a simple algorithm, also presented by the authors, to discard redundancies in the gate structure