High-Speed Analog-to-Digital Converters Utilizing Tunnel Diodes

Two analog-to-digital sequential converters have been devised which combine in one tunnel-diode pair per bit the functions of an amplitude discriminator and memory. In addition, one of the two schemes utilizes each tunnel-diode pair as a delay network. The conversion duration of one of these six-bit converters, which employs germanium 2N559 transistors and gallium arsenide 1N651 tunnel diodes, has been set to 1 ¿sec. Shorter conversion times are possible, but are not required in the present application of that converter as an integral part of an electronic high-speed signal processing system. The use of tunnel diodes presents a significant improvement in the art of converter design by virtue of circuit simplicity and performance. The paper describes the principle and operation of the converters and discusses pertinent considerations for their design. Particular emphasis is given to the discriminator property of a series-aiding tunnel-diode pair. A comprehensive bibliography relating to tunnel-diode switching circuits is attached.