Design and development of SIS mixers for ALMA band 8

In this paper, we report on the design and experimental results of a fix-tuned Superconductor-Insulator-Superconductor (SIS) mixer for Atacama Large Millimeter/submillimeter Array (ALMA) band 8 (385-500 GHz) receivers. Nb-based SIS junctions of a current density of 10 kA/cm/sup 2/ and one micrometer size (fabricated with a two-step lift-off process) are employed to accomplish the ALMA receiver specification, which requires wide frequency coverage as well as low noise temperature. Parallel-connected twin junctions (PCTJ) are designed to resonate at the band center to tune out the junction geometric capacitance. A waveguide-microstrip probe is optimized to have nearly frequency-independent impedance at the probe's feed point, thereby making it much easier to match the low-impedance PCTJ over a wide frequency band. In addition, a superconducting magnet fixed onto the compact mixer block to provide efficient magnetic field coupling is designed. The SIS mixer demonstrates a minimum double-sideband receiver noise temperature of 108 K at the band center and temperatures of less than 167 K over the whole band (for an intermediate-frequency range of 4-8 GHz).

[1]  A. Baryshev,et al.  NbTiN/SiO/sub 2//Al tuning circuits for low-noise 1 THz SIS mixers , 2001 .

[2]  Sheng-Cai Shi,et al.  Parallel Connected Twin SIS Junctions for Millimeter and Submillimeter Wave Mixers: Analysis and Experimental Verification , 1995 .

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

[4]  Hideo Ogawa,et al.  A Fixed-Tuned W-Band Waveguide SIS Mixer with 4.0-7.5 GHz IF , 2003 .

[5]  Arthur W. Lichtenberger,et al.  The ALMA Band 6 (211-275 GHz) Sideband- Separating SIS Mixer-Preamplifier , 2004 .

[6]  J. Stern,et al.  Fabrication and DC-Characterization of NbTiN Based SIS Mixers for Use Between 600 and 1200 GHz , 1998 .

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

[8]  H. Maezawa,et al.  Characterization of NbTiN thin films prepared by reactive DC-magnetron sputtering , 2003 .

[9]  H. Callen,et al.  Irreversibility and Generalized Noise , 1951 .

[10]  Yoshinori Uzawa,et al.  Performance of all-NbN quasi-optical SIS mixers for the terahertz band , 2001 .

[11]  Antti V. Räisänen,et al.  Scaled model measurements of embedding impedances for SIS waveguide mixers , 1985 .

[12]  Ghassan Yassin,et al.  Analytical expression for the input impedance of a microstrip probe in waveguide , 1996 .

[13]  T. M. Klapwijk,et al.  Geometric heat trapping in niobium superconductor–insulator– superconductor mixers due to niobium titanium nitride leads , 2000 .

[14]  Stephane Claude,et al.  A Fixed-Tuned SIS Mixer with Ultra-Wide-Band IF and Quantum-Limited Sensitivity for ALMA Band 3 (84-116 GHz) Receivers , 2004 .

[15]  W. Chang,et al.  The inductance of a superconducting strip transmission line , 1979 .

[16]  Yutaro Sekimoto,et al.  A 385-500 GHz Low Noise Superconductor-Insulator- Superconductor Mixer for ALMA Band 8 , 2006, IEICE Trans. Electron..

[17]  G. Yassin,et al.  Electromagnetic models for superconducting millimetre-wave and sub-millimetre-wave microstrip transmission lines , 1995 .

[18]  Hideo Ogawa,et al.  An Integrated Sideband-Separating SIS Mixer Based on Waveguide Split Block for 100 GHz Band with 4.0–8.0 GHz IF , 2004 .

[19]  Sheng-Cai Shi,et al.  A waveguide-to-microstrip transition with a DC-IF return path and an offset probe , 1996 .