Two-junction tuning circuits for submillimeter SIS mixers

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. >

[1]  M. Wengler.  Submillimeter-wave detection with superconducting tunnel diodes , 1992, Proc. IEEE.

[2]  M. Wengler,et al.  Quantum noise in heterodyne detection , 1987 .

[3]  T. Claeson,et al.  High-frequency limits of superconducting tunnel junction mixers , 1987 .

[4]  M. J. Wengler,et al.  A low noise receiver for millimeter and submillimeter wavelengths , 1985 .

[5]  J. Zmuidzinas,et al.  Low-noise slot antenna SIS mixers , 1995, IEEE Transactions on Applied Superconductivity.

[6]  B. Syrett.  A broad-band element for microstrip bias or tuning circuits , 1980 .

[7]  Jonas Zmuidzinas,et al.  Quasi-optical slot antenna SIS mixers , 1991 .

[8]  T. Klapwijk,et al.  Heterodyne mixing with Nb tunnel junctions above the gap frequency , 1994 .

[9]  J. Tucker,et al.  Quantum limited detection in tunnel junction mixers , 1979 .

[10]  W. Danchi,et al.  Frequency dependence of quasiparticle mixers , 1986 .

[11]  R. Poepel.  Electromagnetic Properties of Superconductors , 1989 .

[12]  Qing Hu,et al.  MM wave quasioptical SIS mixers , 1989 .

[13]  Larry R. D'Addario,et al.  An SIS mixer for 90–120 GHz with gain and wide bandwidth , 1984 .

[14]  R. Genzel,et al.  Measured mixer noise temperature and conversion loss of a cryogenic Schottky diode mixer near 800 GHz , 1989 .

[15]  Marc J. Feldman,et al.  Quantum detection at millimeter wavelengths , 1985 .

[16]  Antti V. Räisänen,et al.  Broad-Band RF Match to a Millimeter-Wave SIS Quasi-Particle Mixer , 1985 .

[17]  P.D. Maker,et al.  A fixed tuned broadband matching structure for submillimeter SIS receivers , 1992, IEEE Transactions on Applied Superconductivity.

[18]  Anthony R. Kerr,et al.  Integrated tuning elements for SIS mixers , 1988 .

[19]  Victor Belitsky,et al.  SIS junction reactance complete compensation , 1991 .

[20]  Raymond Blundell,et al.  Submillimeter receivers for radio astronomy , 1992, Proc. IEEE.

[21]  Thomas G. Phillips,et al.  A broad-band low-noise SIS receiver for submillimeter astronomy , 1988 .