SLLA579 January   2022 ISOUSB211

 

  1.   Trademarks
  2. 1PCB Trace Insertion Loss and Inter-Symbol Interference
  3. 2Transmitter Pre-Emphasis and Receiver Equalizer
  4. 3Selecting an Optimal Pre-emphasis for Your System
  5. 4Eye-Diagrams for 6 inch to 4 feet Traces with all Nine Pre-Emphasis Settings for USB 2.0 Near-end Eye-mask
  6. 5Eye-Diagrams for 6 inch to 4 feet Traces and 5m Cable with all Nine Pre-emphasis Settings for USB 2.0 Far-end Eye-mask
  7. 6Using Receiver Equalizer and Transmitter Pre-emphasis for Channel Loss Compensation Simultaneously
  8. 7Summary

5 Eye-Diagrams for 6 inch to 4 feet Traces and 5m Cable with all Nine Pre-emphasis Settings for USB 2.0 Far-end Eye-mask

Figure 5-1 shows the setup for measuring the far-end eye-mask as specified by the USB 2.0 standard. The ISOUSB211 is placed next to the transmitter, and a USB receptacle connects the FR4 trace to a 5-m USB cable. We used a 5-m cable to account for the worst-case cable loss that is specified by the USB 2.0 standard. The signal is measured at the other end of the 5-m cable for its far-end eye performance.

GUID-20211214-SS0I-ZQPQ-SHQ0-N54ZGFVFB726-low.png Figure 5-1 Far-end Eye Measurement Setup

Figure 5-2 through Figure 5-7 show the eye-diagram measurements with Figure 5-1 setup that uses the transmitter pre-emphasis to compensate for the trace and cable losses. The receiver equalizer is set to 00 throughout the measurements. The transmitter pre-emphasis performances are evaluated by multiplying the EW with EH as shown in Figure 5-7.

Figure 5-2 FE TX_PE 6-inch + 5 m
Figure 5-4 FE TX_PE 2-feet + 5 m
Figure 5-6 FE TX_PE 4-feet + 5 m
Figure 5-3 FE TX_PE 1-feet + 5 m
Figure 5-5 FE TX_PE 3-feet + 5 m
Figure 5-7 Summary of EH*EW metric for FE TX_PE 6-inch to 4-feet Traces