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ST422 - Operation of Mixer Comprising a Series-connected Distributed Superconductor-Insulator-Superconductor Junction Array (Contest winner)

Operation of Mixer Comprising a Series-connected Distributed Superconductor-Insulator-Superconductor Junction Array
 
Wentao Wu1,2, Jie Liu1,3, Wenlei Shan1,3, Member, IEEE,
 
and Cheuk-yu Edward Tong4Member, IEEE
 
 1Purple Mountain Observatory, Chinese Academy of Sciences and Key Laboratory of Radio Astronomy, Nanjing 210008, China
 2University of Chinese Academy of Sciences, Beijing, 10040, China
 3Key Laboratory of Radio Astronomy, Nanjing, 210008, China
 4Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
       
 

Abstract — Mixers comprising series-connected distributed Superconductor-Insulator-Superconductor tunnel junctions (SDJ) are analyzed. Compared to mixers consisting of parallel-connected distributed junctions (PDJ), SDJ mixers offer wider instantaneous bandwidth and higher dynamic range as well as easier magnetic field tuning. However, SDJ mixers are more complex in operation and in design as well. The reason lies in the fact that the large-signal nonlinear equations containing 3N unknowns, with N the junction number, are difficult to be solved. We propose a fixed-point iterative method to solve the nonlinear equations. This method is verified to be effective and efficient and a case study is done to clarify the uniqueness of SDJ mixers in operation.

Keywords (Index Terms) — Large signal problem, Fixed-point iteration, SIS mixer, Series-connected distributed junctions

IEEE/CSC & ESAS SUPERCONDUCTIVITY NEWS FORUM (global edition), January 2015.
Received August 17, 2014; Selected October 1, 2014.  Reference ST422; Category 4.
ASC 2014 manuscript 4EPo2E-05 published online in IEEE Trans. Appl. Supercond. (IEEE XPLORE) DOI: 10.1109/TASC.2014.2363012, on December 18, 2014.