R&S SMA100B - How to Generate a Phase Continuous RF Signal; Phase Continuous Frequency

RF signal configuration
R&S
®
SMA100B
67User Manual 1178.3834.02 ─ 09
f
RF
, Level
RF
= Frequency and level ("Status bar > Frequency and Level") at the output of the downstream
instrument, see also Calculation of f
RF
and Level
RF
)
f
RF Out
, Level
RF
Out
= Frequency and level at the output connector [RF] ("RF > RF Frequency > Frequency" and
"RF > RF Level > Amplitude")
n*f = Multiplication factor ("RF > RF Frequency > Multiplier")
Δf = Frequency offset ("RF > RF Frequency > Offset")
ΔLevel = Power offset ("RF > RF Level > Offset")
Calculation of f
RF
and Level
RF
●
f
RF
=n*f
RF Out
+ Δf
●
Level
RF
= Level
RF Out
+ ΔLevel
4.3 Phase continuous frequency
The R&S SMA100B enables you to generate a phase continuous RF signal over a cer-
tain frequency range. In this mode, the output sine wave signal shows no phase dis-
continuity or glitch when changing the frequency, e.g in sweep mode.
At frequency changes, the switching transitions (intermediate frequencies) cause
spurs. The spurs are due to adjustments in the synthesizer, e.g. adjusting the settings
of dividers, filters, phase detectors can lead to phase discontinuities.
The phase continuous mode freezes the settings of the synthesizer components which
can generate phase discontinuities when adjusted. The R&S SMA100B performs the
frequency changes with the fine resolution synthesizer. The result is a phase continu-
ous change from one frequency to another without transients.
The available frequency range for continuous-phase signal generation is determined
by the fine resolution synthesizer used. The frequency range varies according to the
RF frequency set at the time you activate phase continuous mode.
Equipped with the ultra low phase noise option (R&S SMAB-B711), the R&S SMA100B
enables you to select between two frequency ranges, either to achieve a higher signal
quality or an especially wide frequency range.
4.3.1 How to generate a phase continuous RF signal
To achieve an output sine wave signal with no phase discontinuity or glitch when
changing the frequency, e.g. in RF frequency sweep mode, you can use the phase
continuous mode provided by the instrument.
Activating frequency or phase modulation deactivates phase continuous mode and
vice versa.
To select the phase continuous frequency mode
The folowing example requires, that the instument is equipped with the option
R&S SMAB-B711.
Phase continuous frequency