Digital logic design using negative differential resistance diodes and

Abstract

A digital logic gate circuit including a logic block, clock transistor, bias transistor and a negative differential resistance (NDR) diode which acts as an active load for the circuit. The logic block, comprising a plurality of field effect transistors whose control terminals receive the set of input signals to the logic gate, determines the gate function such as inversion, NAND, NOR, MAJORITY, etc. The clock transistor is connected in series with the logic block and the bias transistor is connected in parallel across this series combination. The terminal of the NDR diode affixed to the common terminal of the bias transistor and the logic block forms the output for the logic circuit. NDR diodes include but are not limited to devices such as tunnel diodes and resonant tunneling diodes (RTDs). The folded I-V characteristic of an NDR diode allows the circuits to operate in a bistable clocked mode, where the circuit output latches its state and changes only when the clock signal is active. The circuit topology allows logic functions to be implemented in a compact manner, thus reducing the propagation delay for the signals, and reducing the overall complexity and delay of arbitrary logic circuits. Thus, performance improvements result from the compactness of logic design as well as the elimination of a pipeline latch area and delay overheads.