Analytical expressions for the design of twin junction tuning in SIS mixers

Abstract We derive general analytical expressions for matching the complex impedance of feeding radio frequency (RF) circuit to a twin junction device in Superconductor-Insulator-Superconductor (SIS) mixers. A unique feature our analysis is that it allows junctions different admittance and an RF with admittance. This provides important design flexibility accommodates fabrication tolerances. then focus on special cases identical junctions, particular those yield simple real impedance. Finally, we curves allow determination parameters given circuit. These designer choose solutions than commonly used quarter-wavelength transmission line separating two SIS which shows not always optimal solution. Moreover, even when commercial software designing circuits, equations will act as guide understanding physics