SERDES Case Study EMI Near-Field Emissions Profiles ... · PDF fileEMI Near-Field Emissions...
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EMI Near-Field Emissions Profiles: Reducing Time-to-Market BACKGROUND A major semiconductor manufacturer had already developed a point-to-point solution (half- duplex) between Serializer/Deserializer (SerDes) devices. In the next generation, the SerDes interface was upgraded by embedding a bidirectional control channel together onto the high- speed serial link for a two-way transmission (full-duplex). Research Objective: Quantify the EMI emissions profile by comparing the half-duplex deserializer to the next generation full-duplex design. Determine whether the full-duplex design impacts the EMI profile and, if so, quantify the difference. Test Method: The design team utilized the on-site EMxpert near-field EMI scanner. They placed the original half-duplex board on the scanner to generate a baseline measurement. After connecting power to the device under test (DUT), they activated the scan on a PC. (Fig. 1) Fig. 1 Test setup for EMI scan Using the identical test setup, the team replaced the baseline board with the new generation full-duplex board. SERDES Case Study
Transcript of SERDES Case Study EMI Near-Field Emissions Profiles ... · PDF fileEMI Near-Field Emissions...
EMI Near-Field Emissions Profiles:Reducing Time-to-Market
BACKGROUND
A major semiconductor manufacturer had already developed a point-to-point solution (half-duplex) between Serializer/Deserializer (SerDes) devices. In the next generation, the SerDes interface was upgraded by embedding a bidirectional control channel together onto the high-speed serial link for a two-way transmission (full-duplex).
Research Objective:
Quantify the EMI emissions profile by comparing the half-duplex deserializer to the next generation full-duplex design. Determine whether the full-duplex design impacts the EMI profile and, if so, quantify the difference.
Test Method:
The design team utilized the on-site EMxpert near-field EMI scanner. They placed the original half-duplex board on the scanner to generate a baseline measurement. After connecting power to the device under test (DUT), they activated the scan on a PC. (Fig. 1)
Fig. 1 Test setup for EMI scan
Using the identical test setup, the team replaced the baseline board with the new generation full-duplex board.
SERDES Case Study
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Test Results:
The EMxpert system generates and displays emissions profiles in real-time and includes both spatial and spectral results. The profile of the baseline system appears in Fig. 2.
Fig. 2 Baseline results - SERDES in half-duplex mode
By comparison, note the emissions scan for the full-duplex scan in Fig. 3.
Fig.3 Emissions profile – SERDES in full-duplex mode
Conclusions:
The team carefully compared the spatial and spectral scan results. They observed no spikes, very similar peak emissions, and a slightly better EMI profile (more blue in the spatial scan) in full-duplex mode than the baseline. By quantifying that no appreciable change occurred in full-duplex mode, (Fig. 3) the team implemented the full-duplex feature with no additional mitigation measures.
SUBSTANTIALLY REDUCED DESIGN TIME
The design team conducted the scans on the EMxpert system in their offices. In a matter of minutes, they obtained the results shown above. Because the emissions profile clearly demonstrated a superior emissions profile, the design required no additional mitigation. To test the new design in a third party chamber would have required that an engineer travel to an off-site test facility for the better part of a day. Access to a chamber could have been weeks away.
To learn more: [email protected]
Acknowledgement: Images and scan results provided by National Semiconductor / Texas Instruments.
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