Semiconductor Science and Technology vol:8 issue:12 pages:2106-2114
Using a series connection of two(three) specially designed resonant tunnelling diodes, we have constructed a two(three) bit analogue-to-digital converter. The measured current voltage characteristics of this series connection have three(seven) regions of negative differential resistance, resulting in four(eight) logic states. The analogue-to-digital conversion function is demonstrated with two resonant tunnelling diodes. A numerical model is proposed to calculate the conversion function when the current voltage characteristics of the separate resonant tunnelling diodes are given. Using this model, we have calculated the conversion function of the three-bit A/D, based on the measured data. The influence of the series resistance on the converter is discussed. The dynamic characteristic of the circuit is investigated. Simulations show that the time response of the converter is determined by the bias circuit.