Unable to Generate Valid PAM4 Eye Diagram and BER Measurements on Stratix 10 SI E-Tile Native PHY

Hardware

• Intel Stratix 10 Development Kit
• E-Tile Native PHY IP
• Single SMA TX and RX channel
• SMA-to-SMA cable (50 Ω)

Software

• Quartus Prime Pro 18.1
• Intel Transceiver Toolkit

Configuration

• PAM4 operation
• Line rate: 51 Gbps
• One TX channel connected directly to one RX channel through an SMA cable
• Design compiles successfully and programming is successful.

Problems Encountered

1. PAM4 Eye Detection Failure

Transceiver Toolkit reports:

"PAM4 eye could not be detected, check lock status and run RX adaptation."

2. RX Adaptation Questions

One-time adaptation completes successfully, but:

• Eye detection still fails.
• BER measurements do not produce a usable eye diagram.

Questions:

• Should continuous adaptation be used instead?
• Is there a recommended adaptation sequence before running Eye Viewer?

3. Eye Diagram Parameters Undefined

After running Eye Viewer:

• Eye Width = Undefined 
• Eye Height = Undefined
• i.e. ratio = (0/0)
• The heatmap returns with full RED and no eye diagram.

The eye diagram is not generated even though the receiver reports lock.

4. BER Test Issues

I am unsure:

• How many bits are required before Eye Viewer can successfully generate a PAM4 heat map.
• Whether there is a minimum BER sample count required for a valid eye diagram at 51 Gbps.
• Whether insufficient captured bits can cause "Undefined" eye width/height.

5. TX Pattern

Currently transmitting a repeating user-defined pattern, for example:

.tx_parallel_data({20{40'b0, 40'h0F0F0F0F0F, 40'b0, 40'h0F0F0F0F0F}})

Questions:

• Is this pattern suitable for PAM4 eye measurements?
• Would PRBS13 or PRBS31 be required instead?

6. Signal Integrity

Questions:

• Can a 50 cm SMA cable (Pasterneck PE3CA1035) reliably carry a 51 Gbps PAM4 signal?
• Is additional equalization or TX pre-emphasis typically required even for short SMA connections?

7. Transceiver Toolkit Configuration

I would appreciate guidance on:

• Recommended Eye Viewer settings.
• Auto Sweep configuration.
• Vertical and horizontal ranges.
• TX FIR tap values.
• RX CTLE/DFE settings.
• Required number of bits before starting the eye scan.

1. What are the common reasons for "PAM4 eye could not be detected" despite PLL/CDR lock?
2. What checks should be performed before running Eye Viewer?
3. PRBS as well as USER sequence, both generate complete RED heatmap, why?
4. How many bits should be accumulated before generating an eye diagram at 51 Gbps?
5. Are there recommended TX FIR, CTLE, and DFE settings for a direct SMA-to-SMA connection?
6. Has anyone successfully generated a PAM4 eye using the Stratix 10 E-Tile Native PHY over SMA? If so, could you share the required configuration or debugging steps?