IEEE Computer Volume 11 Number 5 -- NEW APPLICATIONS
Original Publication Date: 1978-May-01
Included in the Prior Art Database: 2005-Nov-10
Software Patent Institute
Prof. D. A. Michalopoulos: AUTHOR [+3]
THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.
This record contains textual material that is copyright ©; 1978 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Contact the IEEE Computer Society http://www.computer.org/ (714-821-8380) for copies of the complete work that was the source of this textual material and for all use beyond that as a record from the SPI Database.
Prof. D. A. Michalopoulos
California State University, Fullerton
High performance Josephson circuits described by IBM researchers
Major advances in the design and fabrication of ultra-high performance logic and memory circuits were recently reported by IBM research scientists. The devices operate on entirely different principles from the silicon transistor circuits used in all of today's computers. The experimental circuits, made of Josephson junctions, switch in 50 to 100 picoseconds (trillionths of a second), and the memory cells have an access time of 7 nanoseconds (billionths of a second). Even more important than these high switching speeds, the Josephson circuits generate only microwatts of heat -- thousands of times less than high-speed transistor circuits. This permits them to be packed very closely together, an essential quality since with such high switching speeds the time an electrical impulse takes to move from one circuit to the next becomes the major limitation on a computer's speed. In 100 picoseconds, for example, an electrical signal moves about half an inch.
These most recent results of a longrange exploration of Josephson technology by IBM's Research Division were reported at the International Solid State Circuits Conference in San Francisco. The work was done at IBM laboratories in Yorktown, New York, and Zurich, Switzerland.
Josephson circuits operate on entirely different principles from those of the familiar semiconductor circuits in today's computers. Although they require refrigeration to temperatures near absolute zero l -- 459 F or _273c C), they are attractive for fast computers because of their remarkable switching speed (about 10 picoseconds for individual devices) and their very small power requirements. The product of power and delay time is a generally used figure-of~merit for switching circuits. The IBM Josephson circuits have a power-delay product of about 100 attojoules (100 x 10-'8 joules), a thousand times or more better than that of transistor circuits.
Josephson logic circuits.
The logic circuits fabricated at IBM's Yorktown laboratory include AND, OR, INVERT, and latch functions. The circuits are built with what are called Josephson interferometers, each consisting of three Josephson junctions coupled to each other via a common conductor and an inductance. This configuration permits a reduction in capacitance as compared with a single, larger junction and thus allows increased switching speed.
(Image Omitted: An experimental Josephson memory chi...