Superconducting 4–8-GHz Hybrid Assembly for 2SB Cryogenic THz Receivers

We present here the design and characterization of an intermediate frequency (IF) assembly comprising a compact 90° hybrid chip (coupled line coupler - Lange coupler- coupled line coupler), two bias-T circuits for biasing the superconductor-insulator-superconductor (SIS) mixers, and two transmission-line circuits. Specifically, the miniaturized three-section hybrid chip fabricated using thin-film technology utilizes superconducting Niobium (Nb) transmission lines, air bridges to connect the fingers of the Lange coupler (middle section), and is complemented with two bias-T circuits with integrated MIM capacitors. The assembly was designed to ensure amplitude and phase imbalances better than 0.6 dB and ±2°, respectively. Experimental verification of the assembly at 4 K shows good agreement between the measurements and simulations with amplitude imbalance of 0.5 dB and maximum phase imbalance of ±2°. The ALMA band-5 (163-211 GHz) receiver will include such assembly. The receiver tests shows sideband rejection ratio better than 15 dB over the entire RF band, i.e., a systematic improvement of 3-9 dB as compared with the previously reported results.

[1]  Sang-Won Yun,et al.  A design of wideband 3-dB coupler with N-section microstrip tandem structure , 2005, IEEE Microwave and Wireless Components Letters.

[2]  V. Belitsky,et al.  Superconducting 4–8 GHz IF Hybrid for Low Noise mm-Wave Sideband Separation SIS Receiver , 2012, IEEE Microwave and Wireless Components Letters.

[3]  C. Briso-Rodriguez,et al.  Cryogenic Hybrid Coupler for Ultra-Low-Noise Radio Astronomy Balanced Amplifiers , 2009, IEEE Transactions on Microwave Theory and Techniques.

[4]  Victor Belitsky,et al.  Superconducting IF biasing circuit for low-noise cryogenic applications , 2010 .

[5]  V. Belitsky,et al.  Performance of the First ALMA Band 5 Production Cartridge , 2012, IEEE Transactions on Terahertz Science and Technology.

[6]  D. Pozar.  Microwave Engineering , 1990 .

[7]  P. P. Toulios,et al.  Synthesis of Symmetrical TEM-Mode Directional Couplers , 1965 .

[8]  V. Vassilev,et al.  Design and Characterization of a 211–275 GHz Sideband Separating Mixer for the APEX Telescope , 2008, IEEE Microwave and Wireless Components Letters.

[9]  Ricardo Finger,et al.  Integrated Setup for THz Receiver Characterization , 2010 .

[10]  Sang-Won Yun,et al.  A design of wideband 3-dB coupler with N-section microstrip tandem structure , 2005 .

[11]  Miroslav Pantaleev,et al.  SUPERCONDUCTING MICROSTRIP LINE MODEL STUDIES AT MILLIMETRE AND SUB-MILLIMETRE WAVES , 2007 .

[12]  P. Meyer,et al.  A simplified calibration procedure for cryogenic microwave measurements , 1996, 1996 IEEE MTT-S International Microwave Symposium Digest.

[13]  Leo Young,et al.  The analytical equivalence of TEM-mode directional couplers and transmission-line stepped-impedance filters , 1963 .

[14]  L. Young,et al.  Theory and Tables of Optimum Symmetrical TEM-Mode Coupled-Transmission-Line Directional Couplers , 1965 .

[15]  J. Waldram,et al.  Superconductivity of Metals and Cuprates , 1996 .