Development of Cryopackaging and I/O Technologies for High-Speed Superconductive Digital Systems

Yoshihito HASHIMOTO  Shinichi YOROZU  Yoshio KAMEDA  

IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.3   pp.325-332
Publication Date: 2008/03/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.3.325
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Section on Recent Progress in Superconductive Digital Electronics)
single flux quantum,  digital integrated circuit,  multi-chip module,  cryopackaging,  MUX/DEMUX,  switch,  system integration,  

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A cryocooled system with I/O interface circuits, which enables high-speed system operation of superconductive single-flux-quantum (SFQ) circuits at over 40 GHz, and the demonstration of a 47-Gbps SFQ 22 switch system are presented. The cryocooled system has 32 I/Os and cools an SFQ multi-chip module (MCM) to 4 K with a two-stage 1-W Gifford-McMahon cryocooler. An SFQ 4:1 multiplexer (MUX) and an SFQ 1:4 demultiplexer (DEMUX) have been designed to interface the speed gap between the I/O (~10 Gbps/ch) and SFQ circuits (>40 GHz). An SFQ 22 switch chip, in which the MUX/DEMUX and an SFQ 22 switch are integrated, and an 8-channel superconductive voltage driver (SVD) chip have been designed with an advanced cell library for a junction critical current density of 10 kA/cm2. An SFQ 22 switch MCM has been made by flip-chip bonding the switch chip and SVD chip on a superconductive MCM carrier with φ 50-µm InSn solder bumps. An SFQ 22 switch system, which is the switch MCM packaged in the cryocooled system, has been demonstrated up to a port speed of 47 Gbps for the first time.