Logic design based on negative differential resistance characteristics of quantum electronic devices

New quantum electronic devices such as resonant tunnelling diodes and transistors have negative differential resistance characteristics that can be exploited to design novel high-speed circuits. The high intrinsic switching speed of these devices, combined with the novel circuit structures used to implement standard logic functions, leads to ultrafast computing circuits. The new circuit structures presented here provide extremely compact implementations of functions such as carry generation and addition. The most significant impact of these circuits on the field of logic design is the introduction of a totally new set of relative costs of various basic gates; reevaluation of the logic in the light of these new cost functions leads to ultrafast and compact designs.