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IEEE Transactions on Terahertz Science and Technology

Design and Performance of a Sideband Separating SIS Mixer for 800–950 GHz

Andrey V. Khudchenko, M. Yu. Fominsky, Christopher Heiter, S. Heyminck, R. Güsten, Bernd Klein, Ronald Hesper, Andrey M. Baryshev, J. Barkhof, Kirill I. Rudakov, Daniel Montofré, Duc V. Nguyen, V. P. Koshelets, Pavel N. Dmitriev

Published Sep 2, 2019• 21 citations
Publisher

Abstract

We present the design and results of characterization of a new sideband separating (2SB) mixer for 800-950 GHz, based on superconductor-insulator-superconductor (SIS) junctions. This is the first waveguide 2SB SIS mixer demonstrated at such a high frequency. The design is following the classical quadrature hybrid architecture, meanwhile additional attention was put on the reduction of reflections in the RF structure in order to minimize the RF imbalance, to achieve a high image rejection ratio (IRR). The RF waveguide block was manufactured by micromilling and populated by single-ended SIS mixers developed earlier for upgrade of the CHAMP+ high-band array on the APEX telescope. These SIS mixers have double-sideband (DSB) noise temperatures from 210 to 400 K. The assembled 2SB mixer yields a SSB noise temperature from 450 to 900 K, with an IRR above 15 dB in 95% of the band. Comparing the DSB and the SSB sensitivities, we find that the waveguide losses are as low as expected and do not exceed 0.6 dB. The presented mixer is a prototype for use in a 2SB dual polarization receiver planned for deployment on the APEX telescope.

DOI
10.1109/tthz.2019.2939003

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Abstract — We present the design and the experimental results of a fixed-tuned sideband-separating superconductor-insulator-superconductor (SIS) mixer for 385- 500 GHz. The sideband separation is achieved using a quadrature scheme, where two separate DSB mixer blocks are combined with an intermediate waveguide component containing the LO waveguide distribution circuitry and RF waveguide hybrid. The intermediate waveguide piece is fabricated by using copper micromachining, which gives dimensions ’ accuracy better than 1 μm. The RF signal coming from the waveguide hybrid is coupled to the SIS junctions through an E-probe with integrated bias-T. We implemented an on-chip LO injection solution, 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 as a combination of superconducting microstrip lines and slot-lines (branches), which gives almost a lossless solution. With the fabrication accuracy better than 0.5 μm by using optical lithography, the circuitry is proven to give a good performance following the simulations expectations. I.

•Apr 1, 2008•4 citations
We present the design and results of characterization of a new sideband separating (2SB) mixer for 800-950 GHz, based on superconductor-insulator-superconductor (SIS) junctions. This is the first waveguide 2SB SIS mixer demonstrated at such a high frequency. The design is following the classical quadrature hybrid architecture, meanwhile additional attention was put on the reduction of reflections in the RF structure in order to minimize the RF imbalance, to achieve a high image rejection ratio (IRR). The RF waveguide block was manufactured by micromilling and populated by single-ended SIS mixers developed earlier for upgrade of the CHAMP+ high-band array on the APEX telescope. These SIS mixers have double-sideband (DSB) noise temperatures from 210 to 400 K. The assembled 2SB mixer yields a SSB noise temperature from 450 to 900 K, with an IRR above 15 dB in 95% of the band. Comparing the DSB and the SSB sensitivities, we find that the waveguide losses are as low as expected and do not exceed 0.6 dB. The presented mixer is a prototype for use in a 2SB dual polarization receiver planned for deployment on the APEX telescope.
We have developed a Sideband Separating (2SB) Mixer based on superconductor-insulator-superconductor (SIS) junctions for frequency range 790-950 GHz. In the first test this mixer demonstrated the noise temperature from 450 to 900 K and the image rejection ratio above 15dB in 95% of the band. The SIS mixers used here have DSB noise temperature form 220 to 400 K. These results show that RF waveguide hybrid structure for such a high frequencies can be manufactured with losses level below 0.8 dB. It makes attractive possible ALMA upgrade of Band 10 receivers to 2SB option, because the sensitivity for spectral lines observations can be improved by about 30% by using 2SB mixers instead of DSB ones.
A modular sideband-separating (2SB) receiver for 600-720 GHz has been built and tested. The used modular design allows to characterize all the parts separately, including testing of the superconductor-insulator-superconductor (SIS) junctions individually in a double-sideband mode before building them in to the 2SB assembly. The developed 2SB mixer has a single sideband noise temperature below 380 K in the entire operating band and reaches a level of 200 K in the best point. At the same time, the image rejection ratio (IRR) was demonstrated to be better than 11.5 dB over the entire band. However, we have found a discrepancy between the observed and expected performance. To investigate this problem, we have developed and applied methods to characterize RF and intermediate frequency imbalances of a fully assembled 2SB mixer using the SIS junction properties. As result, the IRR of our mixer was found to be limited by the RF imbalance, which is caused by complex standing waves created by reflections from the SIS junctions, the RF hybrid and the RF absorption load.
We present the final results of the development and characterization of the sideband separating superconductor-insulator-superconductor (SIS) mixer for the APEX telescope band 1 (211-275 GHz). The sideband separation is achieved by using a quadrature scheme where the radio frequency (RF) and a local oscillator (LO) power are applied to two identical double sideband SIS mixers. All mixer components, including the LO and RF distribution circuitry, are integrated into a single mixer block. To achieve a compact design we developed a superconducting Lange coupler, based on Nb thin film, which is used as an intermediate frequency hybrid. Typical single sideband noise temperature of 100 K and sideband rejection ratio of about 12 dB and are measured.
We present the results of the development and characterization of the sideband separating (2SB) SIS mixer for the APEX band 1, 211-275 GHz.All mixer components, except the IF hybrid, are integrated into a single mixer block. The sideband separation is achieved by using a quadrature scheme where a local oscillator (LO) pumps two identical SIS mixers. The RF power is divided using a waveguide branch line coupler and directed with 900 phase difference to the ends of the substrate, where each path is coupled to the mixer chip through a waveguide to microstrip transition. Preliminary tests of this 2SB mixer show a sideband suppression ratio of about 12 dB and a typical SSB noise temperature of 80K.
Large-format heterodyne focal plane arrays require highly integrated receiver architectures while maintaining low noise and sufficient sideband rejection, which remains challenging for superconducting SIS mixers at millimeter wavelengths. In this work, we demonstrate, for the first time, a monolithic dual-polarization sideband-separating superconductor-insulator-superconductor (SIS) mixer operating at 2 mm wavelengths (125-163 GHz) on a silicon-on-insulator substrate. The integrated SIS mixer achieves a sideband rejection ratio exceeding 10 dB over the 4-8 GHz intermediate-frequency (IF) band across most of the radio-frequency (RF) range, with a minimum single-sideband (SSB) receiver noise temperature as low as approximately 60 K. As a key building block of the hybrid planar integration (HPI) architecture, this result verifies the feasibility of highly integrated large-format heterodyne focal plane arrays, providing a practical path toward substantially expanding the field of view of millimeter and submillimeter-wave radio telescopes.
Abstract — We present the design and the experimental results of a fixed-tuned sideband-separating superconductor-insulator-superconductor (SIS) mixer for 385- 500 GHz. The sideband separation is achieved using a quadrature scheme, where two separate DSB mixer blocks are combined with an intermediate waveguide component containing the LO waveguide distribution circuitry and RF waveguide hybrid. The intermediate waveguide piece is fabricated by using copper micromachining, which gives dimensions ’ accuracy better than 1 μm. The RF signal coming from the waveguide hybrid is coupled to the SIS junctions through an E-probe with integrated bias-T. We implemented an on-chip LO injection solution, 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 as a combination of superconducting microstrip lines and slot-lines (branches), which gives almost a lossless solution. With the fabrication accuracy better than 0.5 μm by using optical lithography, the circuitry is proven to give a good performance following the simulations expectations. I.