... Microstructure RAS; Nizhny Novgorod; Russia 4 National Institute for Materials Science, Tsukuba 3050047, Japan A Superconducting Integrated Receiver ( SIR ) [1] comprises on one chip a low-noise SIS mixer with quasioptical antenna, an Flux-Flow Oscillator ( FFO ) acting as a Local Oscillator (LO) and a second SIS harmonic mixer (HM) for the FFO phase locking ... Continuous tuning of the phaselocked local oscillator has been realized at any frequency in the range 300-750 GHz. ...