Dac Over-Range Conditions And Scaling - Keysight Technologies N5166B CXG User Manual

Modulated carrier with 0 Hz
baseband frequency offset
DAC Over–Range Conditions and Scaling
When using the baseband frequency offset (at a setting other than 0 Hz), it is possible to create a
DAC over–range condition, which causes the Keysight CXG/MXG/EXG to generate an error. To
minimize this condition with the frequency offset feature, the Keysight CXG/MXG/EXG incorporates
an automatic DAC over–range protection feature that scales down the I/Q data by 1/square root of
2 when the offset is something other than zero. Because it can scale the data by more than what is
actually need, it typically decreases the dynamic range of the waveform. This is especially
noticeable when using a constant amplitude signal such as GSM.
For the Dual ARB Player, this automatic over–range feature can be turned off. When on, it is active
for the Dual ARB signal only when the offset is something other than 0 Hz. The control for the Dual
ARB DAC over–range protection feature is located in the key path as shown in
Keysight CXG, EXG, and MXG X-Series Signal Generators User's Guide
Basic Digital Operation (Option 653/655/656/657)
Modulated carrier with 20 MHz
baseband frequency offset
Spectrum analyzer set to a span of 100 MHz
Setting the Baseband Frequency Offset
LO/carrier feedthrough
Modulated RF signal
Figure 9-14.
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