Application case and specific test method of spectrum analyzer in DDI EMI test of mobile phone screen
DDI (Display Driver IC) is a crucial component in display panels, responsible for scanning digitally processed image signals onto LCD or PDP screens. In the mobile phone industry, especially within Samsung and the broader market, there's a clear shift in display technology trends. Not only major companies but also smaller and mid-sized system suppliers are now entering the DDI field. This technology is increasingly integrated into various electronic devices, particularly mobile terminals, and is often combined with multimedia application processors (APs) to provide comprehensive mobile phone modules for manufacturers.
For electronic products, especially mobile devices, electromagnetic compatibility (EMC) testing is one of the most critical and challenging tests, especially when it comes to radiation noise. The EMI test is essential for ensuring compliance with international standards, and it often presents significant difficulties in suppressing noise from mobile devices.
The following test case involves one of the key tasks we perform during our customers' EMI testing: the DDI EMI Noise test. For example, the RIGOL DSA815 can be used to conduct a basic qualitative analysis of EMI noise from a mobile phone screen’s DDI. The test method and measured results are illustrated below:
Figure 1: Test setup
Solution Configuration:
- Equipment Name: Spectrum Analyzer
- Model and Parameters: RIGOL DSA815 (9kHz–1.5GHz)
- Near-field probe: Germany Langer RF2
- PC Software: Ultra Spectrum
- External preamplifier: Optional
- Fix bracket: Customized as needed
During the test, we need to capture the peak values of 16 frequency points between 700MHz and 1GHz. However, the DSA815 screen can only display up to 10 peaks at a time, so we use PC software for more detailed analysis:
Figure 2: Using PC software for detailed analysis
Test Conditions:
- Frequency range: 700MHz – 1GHz
- RBW/VBW: 10kHz
- Sweep Points: 2000
- Number of Sweeps: 5
- Attenuation: 0dBm
- Test environment: Free from other interference sources
Testing Process:
First, we reset the DSA815 to factory settings, connect the near-field probe, set the start frequency to 700MHz and the stop frequency to 1GHz, set the span to 300MHz, enable the preamplifier, and set the input attenuation to 0dB. By minimizing the instrument's internal noise floor, we can detect more external radiation signals. We set the number of sweeps to 5 and the sweep points to 2000. Then, we place the near-field probe approximately 3mm away from the DDI at the top of the screen while the screen is lit in white. We scan the area systematically from top to bottom and left to right. The results are then analyzed using the host computer software, which displays the peak values of the 16 frequency points.
Process Summary:
The primary application of a spectrum analyzer, as demonstrated in this case, is in EMI pre-testing. It allows for qualitative analysis of EMI noise, helping us refine our products and meet required standards. This approach not only reduces the cost of third-party testing but also saves valuable time during the development cycle.
DOING Water Storage Tanks are drought-resistant water tanks, rainwater collection water tanks, forest fire-fighting water tanks, foldable water tanks, and earthquake relief water tanks.
â— PVC coated cloth Water Tank has the characteristics of environmental protection, novelty, corrosion resistance, anti-oxidation, antifreeze, etc., and is widely used in the packaging and transportation of thousands of liquids such as container flexitanks and drought-resistant water bladders.
â— When in use, the Water Bladder Tank will not be disabled due to seasonal changes. It can be folded and stored when not in use, reducing space occupancy.
â— Water Storage Bladder also has good sealing and corrosion resistance, and can be used to store liquids with pungent odors. Its lifespan is 8-10 years.
Water Bladder Tank,Water Storage Bladder,Bladder Tank,Portable Water Bladder Tank,Portable Water Tanks
Danyang Doing Articles Co.,Ltd , https://www.dydoing.com