Keysight M8121A User Manual page 15

Introduction 1
The three modes have different amplitude vs. frequency responses, which
are shown in the following figure:
Figure 2 DNRZ/NRZ/Doublet Frequency Response
This is only comparing the idealized response of the modes, and ignores
NOTE
the roll off due to finite switching rise times, output RC time constant and
other losses.
Keysight M8121A Arbitrary Waveform Generator User Guide 15