Advances in High-Tc Single Flux Quantum Device Technologies

Keiichi TANABE; Hironori WAKANA; Koji TSUBONE; Yoshinobu TARUTANI; Seiji ADACHI; Yoshihiro ISHIMARU; Michitaka MARUYAMA; Tsunehiro HATO; Akira YOSHIDA; Hideo SUZUKI

doi:10.1093/ietele/e91-c.3.280

Special Section on Recent Progress in Superconductive Digital Electronics

Advances in High-T_c Single Flux Quantum Device Technologies

Keiichi TANABE, Hironori WAKANA, Koji TSUBONE, Yoshinobu TARUTANI, Seiji ADACHI, Yoshihiro ISHIMARU, Michitaka MARUYAMA, Tsunehiro HATO, Akira YOSHIDA, Hideo SUZUKI

Author information

Keiichi TANABE
Superconductivity Research Laboratory, ISTEC
The Institute of Electronics, Information and Communication Engineers
Hironori WAKANA
Superconductivity Research Laboratory, ISTEC
Koji TSUBONE
Superconductivity Research Laboratory, ISTEC
Yoshinobu TARUTANI
Superconductivity Research Laboratory, ISTEC
Seiji ADACHI
Superconductivity Research Laboratory, ISTEC
Yoshihiro ISHIMARU
Superconductivity Research Laboratory, ISTEC
Michitaka MARUYAMA
Superconductivity Research Laboratory, ISTEC
Tsunehiro HATO
Superconductivity Research Laboratory, ISTEC
The Institute of Electronics, Information and Communication Engineers
Akira YOSHIDA
Superconductivity Research Laboratory, ISTEC
The Institute of Electronics, Information and Communication Engineers
Hideo SUZUKI
Superconductivity Research Laboratory, ISTEC
The Institute of Electronics, Information and Communication Engineers

Keywords: superconducting device, single flux quantum device, mixed signal device, high-temperature superconductor

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2008 Volume E91.C Issue 3 Pages 280-292

DOI https://doi.org/10.1093/ietele/e91-c.3.280

Details

Abstract

We have developed the fabrication process, the circuit design technology, and the cryopackaging technology for high-T_c single flux quantum (SFQ) devices with the aim of application to an analog-to-digital (A/D) converter circuit for future wireless communication and a sampler system for high-speed measurements. Reproducibility of fabricating rampedge Josephson junctions with I_cR_n products above 1mV at 40K and small I_c spreads on a superconducting groundplane was much improved by employing smooth multilayer structures and optimizing the junction fabrication process. The separated base-electrode layout (SBL) method that suppresses the J_c spread for interface-modified junctions in circuits was developed. This method enabled low-frequency logic operations of various elementary SFQ circuits with relatively wide bias current margins and operation of a toggle-flip-flop (T-FF) above 200GHz at 40K. Operation of a 1:2 demultiplexer, one of main elements of a hybrid-type Σ-Δ A/D converter circuit, was also demonstrated. We developed a sampler system in which a sampler circuit with a potential bandwidth over 100GHz was cooled by a compact stirling cooler, and waveform observation experiments confirmed the actual system bandwidth well over 50GHz.

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