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Two-junction tuning circuits for submillimeter SIS mixers

Zmuidzinas, Jonas and LeDuc, Henry G. and Stern, Jeffrey A. and Cypher, Scott R. (1994) Two-junction tuning circuits for submillimeter SIS mixers. IEEE Transactions on Microwave Theory and Techniques, 42 (4). pp. 698-706. ISSN 0018-9480. doi:10.1109/22.285084.

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The capacitance of superconducting tunnel junctions can seriously degrade the performance of quasiparticle (SIS) mixers operating in the submillimeter band, so it is essential to provide a circuit for tuning out this capacitance at the operating frequency. In this article, we present two new tuning circuits for SIS mixers which use a pair of SIS junctions connected by an inductance. Compared to previously proposed tuning circuits, ours have a broader bandwidth, are easier to scale to higher frequencies, and may be easier to fabricate. We have constructed quasi-optical mixers which employ these tuning circuits, using Nb/Al-Oxide/Nb SIS junctions defined by optical lithography. The performance of these devices is excellent, giving receiver noise temperatures of 113 K (DSB) at 490 GHz and 230 K DSB at 612 GHz. In addition to demonstrating the effectiveness of our tuning circuit, these results show that quasi-optical mixers can be competitive with or superior to waveguide mixers at submillimeter wavelengths. The mixers continue to perform well at frequencies up to 672 GHz, which is about 95% of the Nb gap frequency.

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Additional Information:© Copyright 1994 IEEE. Reprinted with permission. Manuscript received May 26, 1993; revised August 23, 1993. This work was supported in part by NASA under Grants NAGW-107 and NAG2-744, and NASA/JPL, and an NSF Presidential Young Investigator grant, and in part by the Strategic Defense Initiative Organization (Innovative Science and Technology Office) and the National Aeronautics and Space Administration (Office of Advanced Concepts and Technology). The authors wish to thank G. Engargiola for assistance with the mask layout, J. Carlstrom for constructing the Gunn oscillators, D. Miller and P. Schaffer for assistance in the laboratory, and T. Buttgenbach, J. Carlstrom, J. Kooi, T. G. Phillips, R. Schoelkopf, G. Ugras, and M. Wengler for helpful discussions.
Subject Keywords:aluminium compounds, microwave integrated circuits, mixers, niobium, photolithography, submillimetre wave devices, superconducting integrated circuits, tuning
Issue or Number:4
Record Number:CaltechAUTHORS:ZMUieeetmtt94
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2208
Deposited By: Archive Administrator
Deposited On:15 Mar 2006
Last Modified:08 Nov 2021 19:46

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