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218 Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide
Basic Digital Operation (Option 651/652/654) Preliminary
Understanding Option 012 (LO In/Out for Phase Coherency) with Multiple Baseband Generator Synchronization Preliminary
2x2 MIMO (LO In/Out for Phase Coherency) Configuration
For the 2x2 MIMO (LO In/Out for phase coherency) setup, the LO from the master MXG can be ran
through a power splitter and used as the LO input to both the master and the slave MXGs. No
external source is required.
To generate phase coherent signals for a 2x2 MIMO configuration, the master MXG LO OUT is
connected via a power splitter to the slave LO IN. The LO OUT provides a sufficient amplitude LO
signal when connected directly, to drive the Slave MXG(s), thus providing phase coherency for the RF
output signals. In this example, we show two MXG signal generators with Option 012 connected for a
phase coherent 2x2 MIMO solution. Refer to Figure 8-30.
Figure 8-30 2x2 MIMO (LO In/Out for Phase Coherency) Equipment Setup
3x3 and 4x4 MIMO (LO In/Out for Phase Coherency) Configurations
For a 3x3 and 4x4 MIMO (LO In/Out for phase coherency) setups, an additional analog source is
needed to provide the higher LO power required by the power splitter and the additional
instruments.
Splitting the LO output four ways causes too much loss to drive the LO input of the N5162/82As in
the system. Also, there is no amplitude adjustment to the LO output of the N5162A/82A. To generate
phase coherent signals for a 3x3 and 4x4 configurations with the MXG, an external Master LO is
needed to provide a sufficient amplitude LO input signal to the vector MXGs (refer to Figure 8-31 on
page 219).
NOTE The Master LO is not controlled by any of the Signal Studio software, but must be set
manually—via the RF frequency settings on the master MXG—by the user to the desired
frequency and amplitude.
Note:
To optimize the phase coherence, the same length SMA flexible cable is recommended for the output of the 2–way splitter
connections to the LO IN of the MXGs with Option 012 (see page 216).
To minimize synchronization delay, the Agilent BNC cable 10502A is the recommended cable for the rear panel daisy chain