Radiation linewidth of flux-flow oscillators

The results of linewidth measurements on flux-flow oscillators (FFOs) of a new design with improved parameters are presented. Extensive measurements of the dependence of the free-running FFO linewidth on the differential resistances associated both with the bias current and the control-line current (applied magnetic field) are taken. A profile of the FFO radiation line is measured in different regimes of FFO operation and compared to the theoretical models. A Lorentzian shape of the FFO line is observed both at Fiske steps (FSs) in the resonant regime and on the flux-flow step (FFS) at high voltages. A phenomenological model of the FFO linewidth taking into account all known noise sources (both internal and external) is used to explain the FFO linewidth dependence on the experimental parameters. Finally, we discuss the feasibility of using an electronic phase-locking loop (PLL) over the entire FFO operational frequency band.

[1]  Sergey V. Shitov,et al.  LINEWIDTH OF SUBMILLIMETER WAVE FLUX-FLOW OSCILLATORS , 1996 .

[2]  Andrey L. Pankratov,et al.  Form and width of the spectral line of a Josephson flux-flow oscillator , 2001, cond-mat/0105387.

[3]  Sergey V. Shitov,et al.  Integrated superconducting receivers , 2000 .

[4]  V. Vaks,et al.  Phase locking of 270-440 GHz Josephson flux flow oscillators , 1999 .

[5]  W. Parker,et al.  Linewidth of the Radiation Emitted by a Josephson Junction , 1969 .

[6]  M. Salerno,et al.  Spectral linewidths of Josephson oscillators. , 2001, Physical Review Letters.

[7]  K. Yoshida,et al.  Flux‐flow‐type Josephson oscillator for millimeter and submillimeter wave region. IV. Thin‐film coupling , 1988 .

[8]  Andrey M. Baryshev,et al.  Towards a Phase-Locked Superconducting Integrated Receiver: Prospects and Limitations , 2002 .

[9]  T. Nagatsuma,et al.  Flux-flow-type Josephson oscillator for millimeter and submillimeter wave region. II. Modeling , 1984 .

[10]  Tadao Nagatsuma,et al.  Flux-flow type Josephson oscillator for millimeter and submillimeter wave region , 1983 .

[11]  V. Vaks,et al.  Phase locked 270–440 GHz local oscillator based on flux flow in long Josephson tunnel junctions , 2000 .

[12]  Sergey V. Shitov,et al.  Self-pumping effects and radiation linewidth of Josephson flux-flow oscillators , 1997 .

[13]  W. Luinge,et al.  Flux flow oscillators for sub-mm wave integrated receivers , 1999, IEEE Transactions on Applied Superconductivity.

[14]  T. Nagatsuma,et al.  Flux‐flow‐type Josephson oscillator for millimeter and submillimeter wave region. III. Oscillation stability , 1985 .

[15]  Andrey M. Baryshev,et al.  Superfine resonant structure on IV-curves of long Josephson junction and its influence on flux flow oscillator linewidth , 2001 .