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Figure 26. DAC5682Z Offset Correction Window
5.9 DPD Operation
The DPD Operation section contains the following modes of operation:
Cal Feedback - This button, when selected, will start calibrating the RX attenuation to normalize the
feedback gain.
Start DPD - This button, when selected, will start the DPD adaptation. This button will only become active
after a successful calibration feedback has been performed.
Hold DPD - This button will hold the Look Up Tables (LUT) and stop DPD adaptation.
Resume DPD - This button will resume adaptation after a Hold DPD was issued.
Re-Initialize DPD - This button resets the adaptation.
DPD Control - This button can be used when the DPD is initialized to change the Polynomial order for the
algorithm. The 4 values correspond to the highest order polynomial used for the PA Model, Z = -1, 0, and
+1 Look Up Tables (LUTs). Z = 0 LUT is the memoryless predistortion, while Z= -1 and +1 are correspond
to the memory effects. The default setting is 15 for each, although typically only a value of 9 or less is
needed. Lowering the value will speed up the adaption time of the algorithm.
In most cases, the Model and Z = 0 values should be the same and the Z = -1 and +1 values should be
the same. Often the Z = -1 and +1 values can be less than the Z = 0 value.
To enable DPD Long, click on the "DPD Long Enable" button. Set the desired number of Taps (between
1-10). After the changes have been made, click on the "Update" button. After any changes to either Short
or Long DPD Adaptation, the user must re-initialize DPD.
To write and read from the DSP memory, simply enter the address/data in the correct boxes and then
click on either the "Read" or "Write" button. Consult the GC5325_DPD_Software_User's_Guide for valid
DSP memory locations that can be accessed with this tool.
To set the value in the DSP algorithm, click on the "DPD Control" button, located inside the DPD
Operation window. The DPD Control widow will open as shown in
Figure 27 . Use the pull down menus to
set the values and click on the Set button
26 GC5325 System Evaluation Kit SLWU063F – April 2009 – Revised April 2011
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