Application case and specific test method of spectrum analyzer in DDI EMI test of mobile phone screen

DDI (Display Driver IC) display panel driver IC. It is used to “scan” digitally processed image signals onto LCD or PDP screens. In Samsung mobile phones and even the entire mobile market, the development trend of displays is changing, not only mainstream enterprises, Even small and medium-sized system suppliers are now expanding their business into the DDI field. DDI technology is more widely used in electronic products such as mobile terminals, and combined with multimedia mobile application processor (AP) technology to provide mobile phone modules for more manufacturers. Multimedia application processor. For electronic products, especially the testing of digital mobile equipment EMC is one of the most important experiments in foreign countries, and it is also a test that is difficult to pass, especially the radiation noise of mobile devices is more difficult to suppress.

The following test case is one of the work that we need to test in the EMI test of our customers: DDI EMI Noise test. For example, RIGOL DSA815 can be used to perform simple EMI qualitative analysis on mobile phone screen DDI. The test method and measured results are shown in the figure:

Figure 1: Test connection method

Solution configuration:

Because in the test, it is necessary to display the peak value of 16 frequency points in the range of 700MHz-1GHz in the frequency range, but the maximum peak table displayed in the DSA815 screen is only 10, so it needs to be combined with the PC software for analysis:

Figure 2: Using the PC software for analysis, reading the frequency point test results

Test conditions require:

1. Frequency range: 700MHz - 1GHz

2. RBW/VBW: 10KHz

3. Sweep Point: 2000

4. Number Of Sweep: 5

5. Attenuation: 0dbm

6. The test environment is good, no other complicated interference signals

Testing process:

First restore the DSA815 to the factory default settings, connect the near field probe, set the starting frequency to 700MHz, the termination frequency to 1GHz, the span setting to 300MHz, the preamplifier to open, and the input attenuation to 0db according to the test conditions. By reducing the noise floor of the instrument itself, more radiation signals can be detected. The number of scans is set to 5 and the scan points are 2000. Place the near field probe at the IC at the top of the phone screen (when the phone screen needs to be lit to white). The distance is about 3mm, which is scanned from top to bottom and left and right in turn. The test results can be read on the host computer software to display the peak results of 16 frequency points.

Process summary:

The most typical application of a spectrum analyzer is the application in this case: EMI pre-test. Qualitative analysis of EMI can be made to gradually improve our products and meet the corresponding test standards. Reduce the cost of third-party testing and save more time.

Detailed Product Description

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Elevator Hall Call Panel / Car Operating Panel COP

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Ningbo Xinda Elevator Traction Technology Co., Ltd. , https://www.xinda-elevator.com