A 1-GHz-clock Josephson microcomputer system

Yano, Shinichiro; Hatano, Yuji; Mori, Hiroyuki; Yamada, H.; Nakahara, K.; Hirano, Mikio; Kawabe, U.

doi:10.1109/20.133750

Cited by 16 publications

(6 citation statements)

References 8 publications

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“…These circuits have been demonstrated by Hitachi (16), NEC (13), and Fujitsu (7,11,12). E l m c a l Laboratory (ETL) has fibricated a prototype four-bit Josephson computer and confirmed its functional operation (1 7).…”

Section: High-speed Circuitsmentioning

confidence: 84%

Toward the Realization of a Josephson Computer

Hasuo

1992

Science

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High-quality Josephson junctions, with both electrodes made from niobium and with an aluminum-oxide insulating barrier, were introduced in 1983. This niobium junction is very stable, reliable, controllable, and reproducible. Because of these excellent characteristics, these junctions can be applied to large-scale integrated (LSI) circuits, such as microprocessors having a few thousand gates and a few kilobits of memory. These circuits operate much faster and consume less power than any semiconductor circuit now available. Integrated Josephson circuits are now being tested in a closed-cycle refrigerator. The next step is to design a special-purpose, small-scale Josephson computer and to demonstrate its high performance.

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Section: High-speed Circuitsmentioning

confidence: 84%

Toward the Realization of a Josephson Computer

Hasuo

1992

Science

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“…[1]- [4], it is generally recognized that a fast and dense memory is a bottleneck for a complete JJ computer system. High-speed JJ cache memories have been studied for a long time but few have fully functional circuits with high bit yield [5]-[9].…”

Section: A D Emonstrated High Speed With Low Power Dissipationmentioning

confidence: 99%

A 2-kbit superconducting memory chip

Yuh

1993

IEEE Trans. Appl. Supercond.

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A 2-kbit nondestructive readout memory chip has been built using a Nb/AIO,/Nb Josephson-junction process with a 2.5-pm design rule. A bit-map of 56% functional cells among 1.5 k tested cells, a read-access time of 200 ps and an average cycle time of 500 ps without the decoder, and a power dissipation of 1.6 mW including peripheral circuits are obtained. The decoding time is estimated to be 540 ps. The circuits in this 5 mm by 5 mm, 24-pin chip include 2 k memory cells, 6-b decoder and drivers, serial-to-parallel and parallel-to-serial converters, and circuits for design of testability or timing measurements. More than 14,000 junctions are used on the chip.

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“…Encouraged by this development, several Japanese laboratories demonstrated the possibility of developing a superconductive computer by using Nb technology [1], [2]. Including an 8-bit microprocessor [3], several successful demonstrations were reported.…”

Section: Introductionmentioning

confidence: 97%

Fabrication Technique of Single Flux Quantum ALU by Using Nb Trilayer

Kang

Kim

Hong

et al. 2009

IEEE Trans. Appl. Supercond.

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Nb trilayer process has been serving as the most stable fabrication process of the Josephson junction integrated circuits for more than two decades. Fast development of semiconductor fabrication technology has been possible with the recent advancement of the fabrication equipment. In this work, we took an advantage of those advanced fabrication equipments in developing a superconducting arithmetic logic unit (ALU) by using Nb trilayers. We used DC magnetron sputtering technique for metal depositions and RF sputtering technique for SiO 2 depositions. Various dry etching techniques were used to define Josephson junction areas and various patterns of metallic and insulating layers. Our Nb films were stress-free and had the T c 's above 9 K. To enhance the step coverage of Nb films we used reverse bias DC magnetron sputtering technique. The fabricated 1-bit, 2-bit, and 4-bit ALU circuits were tested at a few kilo-hertz clock frequency as well as a few tens gigahertz clock frequency. Our 1-bit ALU operated correctly at up to 40 GHz clock frequency, and the 4-bit ALU operated at 5 GHz clock frequency.

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A 1-GHz-clock Josephson microcomputer system

Cited by 16 publications

References 8 publications

Toward the Realization of a Josephson Computer

Toward the Realization of a Josephson Computer

A 2-kbit superconducting memory chip

Fabrication Technique of Single Flux Quantum ALU by Using Nb Trilayer

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