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Proceedings Paper

A 385 to 500-GHz SIS mixer the for APEX Telescope
Author(s): Raquel R. Monje; Victor Belitsky; Vessen Vassilev; Alexey Pavolotsky; Igor Lapkin
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Paper Abstract

The Atacama Pathfinder EXperiment (APEX) is a 12 m antenna operating at the Atacama Desert on the Chilean Andes at about 5000 m altitude. APEX would be equipped with a suit of single-pixel heterodyne receivers covering 211 - 1500 GHz frequency range. We present here a design of a sideband-separating superconductor-insulator-superconductor (SIS) mixer for the APEX, receiver Band 3, operating in 385 - 500 GHz band. The receiver uses quadrature scheme with the RF signal passing via a 90-degree waveguide 3 dB hybrid and the LO is divided by a waveguide E-plane Y-junction. The outputs of the waveguide hybrid are coupled to the mixer SIS junctions through an E-probe with integrated bias-T. For the LO coupler, conventional branch waveguide couplers are difficult to manufacture at this high frequency with required accuracy as the branch waveguides become extremely narrow. In order to solve this problem, we propose an on-chip LO injection, where the LO coupler is integrated onto the mixer chip and fabricated together with the SIS junction and the tuning circuitry. The on-chip LO coupler is made of superconducting lines, which gives almost a lossless solution and provides fabrication accuracy better than 0.5 μm by using optical lithography only. Furthermore, the mixer design includes a novel component, an ellipse termination for the idle LO port, made of thin-film resistive material with sheet resistance equal to the transmission line characteristic impedance, which gives very broadband performance using extremely compact area.

Paper Details

Date Published: 6 July 2006
PDF: 9 pages
Proc. SPIE 6275, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III, 62750J (6 July 2006); doi: 10.1117/12.669797
Show Author Affiliations
Raquel R. Monje, Onsala Space Observatory, Chalmers Univ. of Technology (Sweden)
Victor Belitsky, Onsala Space Observatory, Chalmers Univ. of Technology (Sweden)
Vessen Vassilev, Onsala Space Observatory, Chalmers Univ. of Technology (Sweden)
Alexey Pavolotsky, Onsala Space Observatory, Chalmers Univ. of Technology (Sweden)
Igor Lapkin, Onsala Space Observatory, Chalmers Univ. of Technology (Sweden)


Published in SPIE Proceedings Vol. 6275:
Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III
Jonas Zmuidzinas; Wayne S. Holland; Stafford Withington; William D. Duncan, Editor(s)

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