AD9271
Rev. B | Page 44 of
60
4.
In SPI Controller, select Controller Dialog from the
Config
menu. In the PROGRAM CONTROL box, ensure
that Enable Auto Channel Update is selected and click OK.
QUICK START PROCEDURE
The following is a list of the default and optional settings when
using the AD9271 either on the evaluation board or at the
system level design.
5.
In the Global tab of SPI Controller, find the DEVICE
INDEX(4/5)
box. In the ADC column, click S so that the
adjustment in the next step applies to all channels.
If an evaluation board is not being used, follow only the SPI
controller steps.
6.
In the ADC A tab of SPI Controller, find the OFFSET(10)
box and use the drop-down menu labeled Offset Adj to select
the correct LNA offset correction: 25 decimal for the 50 MSPS
speed grade, 26 decimal for the 40 MSPS speed grade, or
31 decimal for the 25 MSPS speed grade.
When using the AD9271 evaluation board,
1.
Open ADC Analyzer on a PC, click Configuration, and
select the appropriate product configuration file.
If the correct product configuration file is not available,
choose a similar product configuration file or click Cancel
and create a new one. See the ADC Analyzer User Manual
7.
Click FFT (
) in Visual Analog.
0
–130
02
0
630
4-
1
19
FREQUENCY (MHz)
AM
P
L
IT
UD
E
(
d
BF
S
)
5
–10
–20
–30
–40
–50
–60
–70
–80
–90
–100
–110
–120
510
15
20
fIN = 3.5MHz @ –1dBFS
LNA = 6×
VGAIN = 1V
FILTER TUNED
HPF = 700kHz
2.
From the Config menu, choose Channel Select. To evaluate
Channel A on the ADC evaluation board, ensure that only
the Channel B checkbox in ADC Analyzer is selected.
Channel A through Channel D correspond to Channel B in
ADC Analyzer.
Channel E through Channel H correspond to Channel A in
ADC Analyzer.
3.
Click SPI in ADC Analyzer to open the SPI controller
software. If prompted for a configuration file, select the
appropriate one. If not, look at the title bar of the window
to see which configuration is loaded. If necessary, choose
Cfg Open
from the File menu and select the appropriate one.
Note that the CHIP ID(1) field may be filled in regardless of
whether the correct SPI controller configuration file is loaded.
Figure 74. Typical FFT, AD9271-50
8.
Adjust the amplitude of the input signal so that the
fundamental is at the desired level. (Examine the Fund:
reading in the left panel of the ADC Analyzer FFT
window.) If the GAIN± pins voltage is low (near 0 V), it
may not be possible to reach full scale without distortion.
Use a higher gain setting or a lower input level to avoid
distortion.
When using the AD9271 evaluation board or system level design,
1.
Click New DUT (
) in the SPI Controller software.
2.
In the Global tab of SPI Controller, find the CHIP
GRADE(2)
box and use the drop-down menu to select
the correct speed grade.
3.
In the ADCGlobal 0 tab of SPI Controller, find the
HIGHPASS(2B)
box and select the Manual Tune box to
calibrate the antialiasing filter.
9.
Right-click the FFT plot and select Comments. Use this
box to record information such as the serial number of the
board, the channel, the input and clock frequencies, the
GAIN± pins voltage, and the date. Press the PRINT
SCREEN
key and save the FFT screenshot if desired.