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600-GHz high-temperature superconducting sub-harmonic mixer coupled using a double-Y-type slot integrated lens antenna

Xiang Gao, Huanxin Li, Ting Zhang, Jia Du, Ken W. Smart, Jianjun Ma, Jianping An

Published Aug 30, 2022• 5 citations
Publisher

Abstract

In this paper, we present a quasi-optically coupled 600-GHz high-temperature superconducting (HTS) sub-harmonic mixer for communication and sensing applications. The mixer features an innovative double-Y-type slot integrated lens antenna, which can efficiently couple the radio frequency (RF) and local oscillator (LO) signals with a small frequency ratio by exciting the half-wave and full-wave resonant current modes on the slot, respectively. Considering the low impedance characteristics of HTS Josephson junctions, a coplanar-waveguide stepped impedance transformer is utilized for minimizing the mismatching loss. A cascaded filter network is designed to prevent the high-frequency signal leakage at both bands while coupling the intermediate-frequency (IF) signal output efficiently. Based on this antenna design and an established HTS step-edge junction technology, a 600-GHz mixer prototype was designed, fabricated and measured, which was compared with the simulation results. The achieved conversion gain and noise temperature are the best performance specs as reported to date for HTS harmonic mixers at comparable frequencies and operating temperatures.

DOI
10.1364/oe.467809

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In this paper, we present a quasi-optically coupled 600-GHz high-temperature superconducting (HTS) sub-harmonic mixer for communication and sensing applications. The mixer features an innovative double-Y-type slot integrated lens antenna, which can efficiently couple the radio frequency (RF) and local oscillator (LO) signals with a small frequency ratio by exciting the half-wave and full-wave resonant current modes on the slot, respectively. Considering the low impedance characteristics of HTS Josephson junctions, a coplanar-waveguide stepped impedance transformer is utilized for minimizing the mismatching loss. A cascaded filter network is designed to prevent the high-frequency signal leakage at both bands while coupling the intermediate-frequency (IF) signal output efficiently. Based on this antenna design and an established HTS step-edge junction technology, a 600-GHz mixer prototype was designed, fabricated and measured, which was compared with the simulation results. The achieved conversion gain and noise temperature are the best performance specs as reported to date for HTS harmonic mixers at comparable frequencies and operating temperatures.
A high-temperature superconducting (HTS) terahertz (THz) frequency down-converter or mixer based on a thin-film ring-slot antenna coupled YBa 2 Cu 3 O 7– x (YBCO)/MgO step-edge Josephson junction is reported. The frequency down-conversion was achieved using higher order harmonics of an applied lower frequency (19–40 GHz) local oscillator signal in the Josephson junction mixing with a THz signal of over 600 GHz, producing a 1–3 GHz intermediate frequency signal. Up to 31st order of harmonic mixing was obtained and the mixer operated stably at temperatures up to 77 K. The design details of the antenna, HTS Josephson junction mixer, the matching and isolation circuits, and the DC and RF performance evaluation are described in this paper.
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A high-temperature superconducting (HTS) terahertz (THz) heterodyne mixer based on a thin-film antenna-coupled YBa2Cu3O7-xstep-edge Josephson junction is presented. The frequency down-conversion from 0.6 THz to an intermediate frequency (IF) of 2 GHz was achieved using high-order harmonic mixing of a local oscillator (LO), thus removing the need to use a second THz source as the LO pumping source. The DC and RF characteristics of the harmonic mixer as well as the relationship of the IF output power versus the harmonic number were experimentally studied and compared with simulated results. Most of our measurements were made at 40 K, but we also observed stable harmonic mixing at 77 K which we believe has not been reported previously in HTS junction mixers.
Abstract This paper presents a monolithic high-temperature superconducting K-band sub-harmonic Josephson mixer using a pair of reverse-biased Josephson junctions (JJs), which are biased using reversed DC current. The sub-harmonic mixer can provide higher conversion gain and stronger rejection of the even-order harmonics of the local oscillator signal. A matching circuit with several bandpass filters (BPFs) is designed to match the junctions and achieve a maximum conversion gain. Based on the circuit configuration and using the established Verilog-A JJ mixer model, transient simulation has been done in the circuit simulator. An electromagnetic (EM) model is built and simulated in a full-wave simulation environment, and the results reveal that the design realizes very low loss at 25 GHz, excellent port isolation and high conversion efficiency. A prototype has been fabricated and tested in a cryocooler at operating temperatures of 40 K and 20 K. Measurements have experimentally verified the novel radio frequency design and simulation results. Maximum conversion gains of −10.5 dB and −6.5 dB were obtained at 40 K and 20 K, respectively, with a bandwidth greater than 400 MHz and outstanding gain linearity. It is also predicted that the mixer performance can be further improved with higher critical current I c values and identical or similar I c values between two parallel junctions.
Wireless communication and sensing are moving from microwave, millimeter-wave into the terahertz (THz) frequency regime to meet the fast growing demand of ultrahigh data-rate communications and super resolution imaging. Faced with severe atmospheric absorption attenuation and the lack of power efficient transmitting source at the higher band, ultrasensitive and cost-effective receiver frontend technology is required for advanced THz wireless systems. To date, the most sensitive heterodyne mixers, the key components of frontend receiver systems, are based on low-temperature superconducting materials that operate at liquid helium (4.2 K) temperature range, requiring expensive and bulky cryogenic cooling systems thus hindering them from commercial applications such as wireless communications and sensing. In this article, we present a 340 GHz double-sideband fundamental mixer based on thin-film antenna-coupled high-temperature superconducting (HTS) Josephson junction that operates at a much higher temperature range attainable with smaller and cheaper cryocoolers. Based on our innovative work in terms of advanced device circuit and on-chip antenna designs, accurate parametric simulation analyses, and Josephson junction parameter optimizations, the reported mixer exhibits a measured noise temperature of 470 and 780 K at operating temperatures of 20 and 40 K respectively at 340 GHz, a performance significantly higher than any HTS THz mixers reported to date.
A 220-GHz Miniaturized Antenna-Coupled Mixer Based on Bi2Sr2CaCu2O8\mathbf{Bi}_{2} \mathbf{Sr}_{2} \mathbf{CaCu}_{2} \mathbf{O}_{8}Bi2​Sr2​CaCu2​O8​ Josephson Junction Array
This paper presents the design and simulation of a 220-GHz miniaturized slot-antenna-coupled high-temperature superconducting (HTS) mixer, which integrates the HTS junction and the choke filter on one single substrate. The presented mixer utilizesBi2Sr2CaCu2O8\mathbf{Bi_{2}}\mathbf{Sr_{2}}\mathbf{CaCu}2\mathbf{O_{8}}Bi2​Sr2​CaCu2O8​(BSCCO) intrinsic Josephson junction array as the nonlinear mixing device. To compensate the parasitic capacitance of the BSCCO junction, a short transmission line is used as an inductance for improving impedance matching between the slot antenna and the BSCCO Josephson junction array. The simulation results show that the proposed mixer achieves a conversion gain and noise temperature of -6.74 dB and 266.28 K @ 50K, respectively.