A 10 GHz digital amplifier in an ultra-small-spread high-Jc Nb/Al-AlOx/Nb integrated circuit process
Bhat, A.
Xiaofan Meng
Whiteley, S.
Jeffery, M.
van Duzer, T.
Dept. of Electr. Eng. & Comput. Sci., California Univ., Berkeley, CA;
This paper appears in: Applied Superconductivity, IEEE Transactions on
Publication Date: Jun 1999
Volume: 9,
Issue: 2, Part 3
On page(s): 3232-3235
Meeting Date: 09/13/1998 - 09/18/1998
Location: Palm Desert, CA, USA
ISSN: 1051-8223
References Cited: 14
CODEN: ITASE9
INSPEC Accession Number: 6356778
Digital Object Identifier: 10.1109/77.783717
Current Version Published: 2002-08-06
Abstract
We describe a Josephson amplifier fabricated in a high-Jc
process, which is operational to speeds of at least 10 GHz, the
highest reported for a voltage-state amplifier. The amplifier converts
~200 μV digital signals to ~5 mV at 10 GHz and could be used as an
interface between two superconducting systems. The bit-error-rate of the
circuit was ~5×10-12 at 5 GHz, the lowest reported;
bit-error-rate measurements at 10 GHz were not possible. A high-Jc
process which was used to fabricate the amplifier was developed
at UC Berkeley with extremely low Ic spreads; at ~9.4 kA/cm
2 σ as low as 0.6% was observed. At ~10 kA/cm2
, the typical junction linear dimensions are 1.5 ~ 2 μm, sizes
for which it is not possible-with available tools-to make reliable vias
that are smaller than the junction. We use a nonplanarized junction
process, where the via for contact of a wiring layer to a junction can
be larger than the junction
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