We have used DS90UB948 and DS90UB949 Serializer and Deserializer parts in our one of the display project.
In project, Serializer EVM board connected to processor board and Deserializer IC mounted in display board and both the boards are interfaced through co-axial cable.
When testing Radiated emission(EMC Class-B) only for Deserializer board (Serializer and processor board kept outside the chamber) It was failed in some of the frequency range. Vertical and Horizontal scan result available below.
Now we are working with failure analysis and we got know that, there is option in Serializer IC to reduce EMI by enabling spread-spectrum.
Please let us know how to enable spread-spectrum in Serializer?
horizontal and vertical scan result:
|
Vertical Results |
|||||||
|
Frequency |
QP |
Limit |
Margin |
TWR |
Cable |
Antenna |
EUT Angle |
|
MHz |
dBuV/m |
dBuV/m |
dB |
cm |
dB |
dB |
Deg |
|
33.007 MHz |
34.77 |
30 |
-4.77 |
112 |
0.77 |
19.96 |
198 |
|
34.195 MHz |
36.31 |
30 |
-6.31 |
100 |
0.79 |
19.83 |
198 |
|
34.559 MHz |
35.6 |
30 |
-5.6 |
100 |
0.79 |
19.79 |
198 |
|
35.31 MHz |
35.79 |
30 |
-5.79 |
100 |
0.8 |
19.63 |
198 |
|
35.737 MHz |
31.88 |
30 |
-1.88 |
138 |
0.81 |
19.47 |
198 |
|
190.87 MHz |
18.27 |
30 |
11.73 |
100 |
1.69 |
9.72 |
131 |
|
216.05 MHz |
24.53 |
30 |
5.47 |
400 |
1.85 |
11.24 |
260 |
|
Horizontal Results |
|||||||
|
Frequency |
QP |
Limit |
Margin |
TWR |
Cable |
Antenna |
EUT Angle |
|
MHz |
dBuV/m |
dBuV/m |
dB |
cm |
dB |
dB |
Deg |
|
196.33 MHz |
27.01 |
30 |
2.99 |
400 |
1.72 |
9.92 |
143 |
|
223.51 MHz |
30.57 |
30 |
-0.57 |
350 |
1.9 |
11.79 |
30 |
|
229.29 MHz |
32.01 |
30 |
-2.01 |
350 |
1.93 |
12.22 |
74 |
|
229.55 MHz |
32.61 |
30 |
-2.61 |
369 |
1.93 |
12.24 |
75 |
