Vp. Koshelets et al., Superfine resonant structure on IV-curves of long Josephson junction and its influence on flux flow oscillator linewidth, IEEE APPL S, 11(1), 2001, pp. 1211-1214
The Josephson Flux Flow Oscillator (FFO) has proven to be a perfect on-chip
local oscillator for integrated submm receivers; a noise temperature (DSB)
below 100 K has been achieved at 500 GHz. Recently a FFO linewidth as low
as 1 Hz has been measured in the frequency range 210 - 440 GHz, A new techn
ique for both linewidth measurements and phase locking of the FFO is develo
ped; this method employs an off-chip harmonic multiplier, By measuring the
frequency of the FFO radiation emission, its IV-curve (IVC) can be reconstr
ucted with an accuracy better than 1 nV, A superfine resonant structure wit
h a voltage spacing of about 20 nV and extremely low differential resistanc
e has been observed in the FFO IVCs, This resonant structure modifies the p
erformance of the FFO compared to the one expected from the "averaged IVC".
The influence of this resonant structure on phase locking is discussed. Al
so results of FFO phase noise measurements are presented.