Superconducting Technology Assessment - nitrd

■ Superconductor processors will use a partitioned microarchitecture, where processing
occurs in close proximity to data.
■ In order to achieve high sustained performance, aggressive architectural techniques
will be used to deal with memory access latency.
Processors and Memory
The capability in 2010 should be >1 million JJs per cm 2 , implying >100,000
gates per cm 2 with clock speed >50 GHz.
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The technology should be brought to the point where an ASIC logic designer
will be able to design RSFQ chips without being expert in superconductivity.
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An advanced 90 nm VLSI process after 2010 should achieve
~ 250 million JJ/cm 2 and circuit speeds ~ 250 GHz.
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Three attractive memory candidates are at different stages of maturity:
– Hybrid JJ-CMOS memory.
– Single-flux-quantum superconducting memory.
– Superconducting-magnetoresistive RAM (MRAM).
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A complete suite of CAD tools can be developed based primarily on corresponding
tools for semiconductors.
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Total investment over five-year period: $119 million.
Processors
The complexity of RSFQ logic chips developed to date has been constrained by production facility limitations and
inadequate design tools for VLSI. Although all demonstrated digital chips have been fabricated in an R&D environment
with processing tools more than a decade older than CMOS, impressive progress has been made. The panel
concludes that, given the design and fabrication tools available to silicon technology, RSFQ circuit technology can
be made sufficiently mature by 2010 to support development of high-end computers.
Ready for Investment
The panel concluded that with the availability of a stable VLSI chip production capability, RSFQ processor technology
will be ready for a major investment to acquire a mature technology that can be used to produce petaflops-class
computers starting in 2010. (“Mature technology” means that a competent ASIC digital designer with no background
in superconductor electronics would be able to design high-performance processor units.) This judgment
is based on an evaluation of progress made in the last decade and expected benefits of an advanced VLSI process
in a manufacturing environment. Although RSFQ circuits are today relatively immature, their similarity in function,
design, and fabrication to semiconductor circuits permits realistic extrapolations.
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