integrated with an SIS mixer, a superconducting Flux Flow Oscillator (FFO) acting as Local
Oscillator (LO) and a second SIS harmonic mixer (HM) for FFO phase locking. Free-running
FFO linewidth well below 10 MHz is required to ensure phase-locked operation of an SIR.
Comprehensive experimental study of the Nb-AlOx-Nb FFO linewidth and other main
parameters has been carried out in order to achieve this goal. Essential dependence of the …