Reference Oscillator
R&S
®
SMA100B
270User Manual 1178.3834.02 ─ 05
If the EFC is applied in combination with an external PLL (phase locked loop), the
PLL bandwidth must be smaller than the bandwidth of the external tuning signal.
●
FM-DC mode
If the measurement requires higher PLL bandwidth, we recommend that you use
the external FM modulation (DC coupling) in low noise mode.
The FM-DC mode yields a fixed tuning sensitivity that is independent of the RF out-
put frequency and corresponds to the selected FM deviation.
Sharing the 1 GHz reference frequency to obtain phase-coherent signals
Compared to 10 MHz, a 1 GHz reference signal significantly improves the achievable
phase stability between two signal sources. Because the synchronization increases by
a factor of 100, the relative phase fluctuations between the sources can be reduced.
1 GHz at connector Ref In 1GHz and 1 GHz at Ref Out 1GHz
●
External f
Ref
= 1 GHz
●
Source = "External"
●
External Reference Frequency = "1 GHz"
●
1GHz Reference Output = "1 GHz"
Using external reference source
If you have a clean external reference signal with 10 MHz or 100 MHz frequency, for
example, you can directly pass it to the output. The signal quality remains the same.
10 MHz/100 MHz at connector Ref Out and Ref In
●
External f
Ref
= 10 MHz or 100 MHz
●
Source = "External"
●
Reference Output = "10 MHz/100 MHz" or "Input Signal (loop through)"
●
Set the synchronization bandwidth according to the requirements of the applica-
tion.
Figure 8-2: Synchronizing instruments with a 10 MHz external reference signal
Ref. Frequency Source = e.g. Rohde & Schwarz signal analyzer
f
Ref
= 10 MHz/100 MHz/1 to 100 MHz external reference frequency
Ref In, Ref Out = Connectors
You can forward reference frequency between 1 MHz and 100 MHz directly to the out-
put in the same way.
●
External f
Ref
= 1 MHz to 100 MHz
(1 MHz to 100 MHz at connector Ref In and Ref Out)
●
Source = "External"
Using the Reference Frequency for Instruments Synchronization
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