Instrument Function
R&S
®
SMU200A
200Operating Manual 1007.9845.32 ─ 15
5.5.3.2 Phase Continuous Frequency Setting
The phase continuous mode can be enabled in the "Phase Continuous Frequency Set-
tings" section of the "Frequency" menu. In this mode, the output sinewave is phase con-
tinuous, i.e. there is no phase discontinuity or glitch when changing the frequency.
At the transition from one frequency to another an intermediate frequency (switching
transient) occurs, which causes spurs (see figure below). The transient is due to changes
of the synthesizer settings (e.g. dividers, filters, phase detectors).
Fig. 5-7: Transition for a 1 kHz step at 1 GHz without phase continuous mode active. For the graphical
display the signal is down converted into the kHz range.
The phase continuous mode freezes the settings of the synthesizer (e.g. dividers, filters,
phase detectors) which could generate phase discontinuities when changed. The fre-
quency change is effectively performed by changing the fine resolution synthesizer. This
allows a phase continuous change from one frequency to another without any transients
(see figure below).
RF Signal and Analog Modulations - RF Block
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