1.2.4.2 DFE Mode

DFE is used above 6.8 Gbps for long and medium reach channel, and above 10.3125 Gbps for short reach channel. The following example is based on long channel at 12.5 Gbps. The transceiver tunes the best value with following system attributes:

  • Channel: 34-inch backplane channel and 4-inch PolarFire Evaluation Kit PCB trace.
  • Tx Amplitude: 800 mV
  • De-emphasis: 0 dB
  • Tx Termination: 150Ω
  • Data Rate: 12.5 Gbps
  • Data pattern: PRBS31

The following figure shows the eye obtained in SmartDebug. The system works with zero bit errors.

Figure 1-20. Eye from SmartDebug at 12.5 Gbps – Long Backplane Channel

The blue portion shows the zero bit error rate region.