Using the Software
4.1.3
Step 3: Loading Channel 1 Configuration Data
1. To load the TX Channel 1 devices of the GC5325EVM, including DAC5682Z, CDCM7005, attenuators,
RF switches and GC5325, go to the "device button", located in the upper left side of the GUI, and
change the current value from
“
0
”
to
“
1
”
. This now allows the GUI to communicate to the Channel 1
devices. To communicate with Channel 0 devices, simply switch this setting back to
“
0
”
.
2. Click on the
“
Load EVM
”
button:
This results in a significant amount of information to be displayed in the programs DOS window and
takes about 30 seconds. When it is finished, the
“
Cal Feedback
”
button in the DPD Control section is
enabled and the GUI message window displays
“
EVM downloading is done
”
The DAC5682Z DLLlock
indicator is green on the GUI reflecting the DAC5682z is locked to the GC5322.
3. Both channels are now configured and ready for test.
4.2
Operating the GC5325SEK
4.2.1
Controlling the Analog Signal and Running DPD
1. The test signals are now flowing through both GC5325 devices and the TX sections of the card. DPD
has not started adaption at this point. The user first verifies the quality of the TX and FB path signals
using the internal Capture Buffers in the GC5325s. For this test, the system uses the onboard loop
back capability to loop the TX signal from Channel 0 back to the FB path. To enable this test, do the
following:
(a) Verify that the Loop back checkbox (located in the lower left section of the GC5325 GUI) is
selected. If not, click on the box to select it. When Channel 0 loop back is enabled, LED D6 (next to
SMA labeled TX0_OUT) is illuminated. When this is disabled, the channel is transmitting through
this SMA and the LED is off. On power up, both channels come up in loop back mode to prevent
from possibly overdriving external PAs. For Channel 1, LED D5 is illuminated when set to loop back
mode.
(b) The TX attenuator and RX attenuator settings can be adjusted in 0.25-dB increments by selecting
the TX atten and RX atten boxes located in the bottom left side of the GUI. A value can be entered
or the existing value changed by using the keyboard up and down arrows. The TX attenuator can
be set from zero (minimum attenuation) to 31 (maximum attenuation) in 0.25 incremental values.
For this example, set the TX atten to 5.
Now click on
“
Cal Feedback
”
to set the RX attenuator for unity gain. Note that a complete path for the
signal from DAC to ADC is required, either loopback or though external hardware. If successful, the RX
Atten setting changes between 0 and 31. For the default internal loopback case, the RX attenuation
typically is in the 5- to 15-dB range.
If the power is not sufficient for the feedback ADC, you get the following error.
An error has occurred where the feedback power is too high
–
in this case, attenuation must be added
to the FB path input. If the Cal feedback is successful, the GUI status window displays the following
message: "Calibration successful. RX attenuation set to XX," where XX is the setting programmed into
the feedback attenuator. The Start DPD and Capture Buffer buttons now become active. Before
Starting DPD, the user must examine the data from the capture buffers.
Click on the
“
re-capture
”
button. This displays the DPD and Feedback output buffers on the GUI
window, and now looks like the screen in
18
GC5325 System Evaluation Kit
SLWU063F
–
April 2009
–
Revised April 2011
Copyright
©
2009
–
2011, Texas Instruments Incorporated
