A Circuit for Tuning Superconductor–Insulator–Superconductor Mixers Using Distributed Tunnel Junctions

概要

論文の詳細を見る
A circuit that produces broadband impedance matching with low-current-density junctions at submillimeter wavelengths for tuning superconductor–insulator–superconductor (SIS) mixers is described; it consists of half-wavelength distributed SIS junctions connected alternately by half-wavelength microstrip lines. It is made of Nb and was designed for two practical source impedances using numerical calculation based on the Mattis–Bardeen theory of the anomalous skin effect at 660 GHz, assuming SIS junctions with a current density of 5 kA/cm2. An SIS mixer tuned using this circuit had a large fractional bandwidth of more than 18%, below $-10$ dB matching, even though the assumed $\omega C_{\text{J}}R_{\text{N}}$ product was about 16. Investigation of the mixer performance using Tucker's quantum theory of mixing showed that it has excellent broadband and low-noise characteristics compared with conventional mixers consisting of half- or full-wavelength distributed elements.
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
2003-01-15