A wideband terahertz high-T_csuperconducting Josephson-junction mixer: electromagnetic design, analysis and characterization

Abstract

This paper presents a wideband terahertz (THz) mixer based on a thin-film antenna-coupled hightemperature superconducting (HTS) YBa2Cu3O7-x (YBCO) step-edge Josephson junction. The HTS mixer enables the flexible harmonic mixing operation at multiple THz bands with one same microwave local oscillator (LO) source, and features very wide intermediate-frequency (IF) or instantaneous bandwidth. In order to optimize the frequency down-conversion performance of the mixer, systematic electromagnetic design and analysis have been carried out to improve the power coupling of THz radiation as well as wideband transmission of microwave signals. Experimental characterization of a fabricated device prototype has demonstrated that the mixer exhibits good performance at both the 200 GHz and 600 GHz bands. Detailed measurement results including the DC characteristics, LO pumping requirement, frequency response, mixing linearity and conversion gain are presented in this paper. IntroductionOver the last few years, there is a drastically increasing demand for high speed wireless transmission in various electronics application scenarios, such as short-range intra-machine and inter-board communications, medium-range wireless local and personal area networks, and long-range highthroughput wireless directional links. Benefitting from the considerable absolute bandwidth, terahertz (THz) wireless communication [1,2] is envisioned as a promising technology to effectively alleviate the spectrum scarcity and capacity limitations of current wireless systems. However, there

Full EM Design Method For HTS MMIC Josephson Mixers

“…TS materials have ultra-low surface resistance at frequencies below 100 GHz, which has been applied to make filters and resonators with superior performance [1][2][3]. The lownoise and high non-linearity properties of the HTS Josephson junctions make them ideal for the key component of mixers [4][5][6][7]. A series of HTS MMIC Josephson mixers, ranging from 7 GHz to 36 GHz, have been developed at CSIRO, Australia, of which the YBa2Cu3O7-x (YBCO) step-edge Josephson junctions are integrated monolithically with a series of YBCO filters to achieve better performance [8][9][10][11].…”

Noise and conversion performance of a high-Tc superconducting Josephson junction mixer at 0.6 THz

“…For sub-millimeter and THz wave applications, due to the limited transmitting power and severe atmospheric absorption attenuation, 1 the system receivers are required to be extremely sensitive and thus capable of detecting the weak arriving signals. High-Tc superconducting (HTS) Josephson-junction mixers [2][3][4][5][6][7] have been shown to be promising candidates for THz receiver frontends considering their high sensitivity, low noise, low local oscillator (LO) power requirement, and relatively cheaper cryogenic costs compared to that for cooling low-Tc superconducting (LTS) devices.…”

“…The radiation performance of the antenna had been optimized using the software Computer Simulation Technology (CST) Microwave Studio. 7 By taking advantage of the log-periodic impedance fluctuation characteristics, the ZA was tuned as small as (40.6 + 2.2j) Ω at the operating frequency of 0.6 THz for reducing the antenna-junction mismatch. In addition, the IF microwave readout network had been designed for matching to 50 Ω.…”

“…The details of the electromagnetic design for our presented mixer were previously reported. 7 The noise calculation and measurement described in this letter is at the fundamental mixing mode. First, the three-port model method 9 was employed to solve a noise-driven nonlinear pump equation in the time domain for obtaining the frequency-conversion and noise-correlation matrices.…”

“…The HTS THz mixer chip was implemented using the CSIRO established step-edge YBCO junction technology 10 and more details of device fabrication and module packaging can be found in Ref. [7]. Figure 2 illustrates the experimental set-up for mixer noise and conversion gain characterizations.…”