NFG0QHB372HS2
Noise suppression technologies/case study introduction (Consumer)
Noise Suppression for USB4 (4)
INDEX
- USB4 Standard and Its Adoption
- Integration of USB and Thunderbolt
- Specifications and Comparison of Thunderbolt 3 and USB4
- Anticipated Noise Issues with USB
- Noise Suppression Measures for USB4
- Radiated Noise Measurement
- Measurement of radiated noise
- Intrasystem EMC: Overview of DUT (Thunderbolt 3 Compatible Add-in Card)
- Intrasystem EMC: Assessment of Impact on Wi-Fi Reception Sensitivity
- Intrasystem EMC: Measurement Results of Wi-Fi Reception Sensitivity (No Noise Suppression Measures)
- Intrasystem EMC: Assessment of Noise Entering the Antenna
- Intrasystem EMC: Measurement Results for Noise Entering the Antenna (No Noise Suppression Measures)
- Intrasystem EMC: Measurement of Nearfield noise (No Noise Suppression Measures)
- Intrasystem EMC: Noise Suppression Component Insertion Location
- Intrasystem EMC: Measurement Results of Reception Sensitivity (After Implementation of Noise Suppression Measures)
- Intrasystem EMC: Measurement Results for Noise Entering the Antenna (After Implementation of Noise Suppression Measures)
- Signal Waveform Check: Eye Pattern Measurement Procedure
- Signal Waveform Check: Eye Pattern Measurement
- Conclusion
17. Signal Waveform Check: Eye Pattern Measurement Procedure
Because a common mode choke coil is used as a noise suppression measure on the signal line, its effect on signal quality was also checked. The signal for Thunderbolt 3 was checked.
A Thunderbolt 3 test pattern was output from the DUT, and the signal quality after passing through the CMCC was checked.
18. Signal Waveform Check: Eye Pattern Measurement
We checked whether use of the common mode choke coil has any effect on signal quality.
A Thunderbolt 3 test pattern was output from the DUT, and the signal quality after passing through the CMCC was checked.
Even if a common mode choke coil is used, the signal waveform quality is identical to that before the filter was inserted, and the Thunderbolt 3 compliance test was passed.
Because USB4 also uses the same signal speed (Max. 20 Gbps), the waveform test is expected to be passed.
Our recommended common mode choke coils
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Noise suppression can be implemented using a compact, slim type having a size of 0.65×0.50×0.30 mm with dimensional error of ±0.05 mm without affecting the signal waveform of the high-speed differential transmission line.
19. Conclusion
- Radiated Noise
- A USB4 operating environment was simulated for conducting a noise assessment.
- In the 30 to 1000 MHz and the 1 to 18 GHz range, there was no problem with radiated noise.
- Wi-Fi Reception Sensitivity
- The Wi-Fi reception sensitivity was reduced when PCI Express, DisplayPort 1.4, and Thunderbolt 3 were operating.
- In particular, noise in the 2.4 GHz band was found from the board wires when USB 3.1 Gen 2 was operating.
- The same noise is expected to be generated during USB4 operation.
- Use of a common mode choke coil eliminated the drop in Wi-Fi sensitivity.
- Signal Quality
- The following recommended components can be used to implement noise suppression measures without affecting the signal quality.
Our recommended common mode choke coils
Because the cutoff frequency is high, the effect on high-speed signals is low, and the attenuation characteristics peak is deep, which enables superior noise suppression characteristics.