AN 952: Intel® Arria® 10 and Intel® Stratix® 10 HDMI 2.1 System Design Guidelines

ID 709310
Date 6/21/2022
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4.3.2. FPGA RX Settings

You must use a redriver on the PCB panel to ensure compliance to RX CTS and HDMI 2.1 cable loss. Intel products do not support non-compliant cables. The equalization is dependent on overall system reach design; in a typical scenario, 16 dB is sufficient, while longer traces on larger PCB panels require higher equalization.

You can use flex cables instead of a large PCB panel for a better cost-to-performance ratio. Use link training methodology to evaluate if such cables match your setup. Validation setup uses generic jitter tolerance methodology to meet HDMI 2.1 CTS requirements.

Below is a summary of targeted loss calibration:
Table 7.  Targeted loss calibration
Insertion Loss : 20.11 dB
Spec Calibrated
Amplitude 800-1200 mV -
RJ 0.2 UI 1.31 ps 1.224 ps 0.12 UI
DJ 0.35 UI 29.2 ps - -
BUJ 0.15 UI 12.5 ps 12 ps 0.12 UI
SJ/PJ 0.1 UI 8.33 ps 9.33 ps 0.1 UI
Eye Height 100 mV - 97.1 mV
Eye Weight 29.17 ps - 31.5 ps

The jitter (BUJ) interpretation varies. Focus on the entire system level with all components account for 1 UI budget. provides WCM cable that shows the cable loss parameter. The stressed signal feeds into RX to establish jitter tolerance. The following table lists the recommended settings:

Table 8.  FPGA RX Recommended Settings
Component Intel® Arria® 10 FPGA Redriver

(TI DS125MB203)

Adaptation Mode Manual CTLE, TX FFE EQ DeEmp VOD
VGA Gain 2 - -
DC Gain 1 - -
AC Gain 3 Level4 Level 0-2



Vpp Amplitude - - 0.8

Do note that a 2 UI TX length at 6 Gbps at Test Point 1 is a mandate by HDMI 2.1 CTS.

All settings listed in this document are available in Intel® Quartus® Prime. You can update the settings to reflect the need of each design requirements as well as loss factor.

To mitigate variability in customer loss profiles:

  1. Isolate and confirm that the root cause is the transceiver link.
  2. Apply link tuning methodology.
  3. Refer TTK (transceiver toolkit):
    • Evaluate link stability and robustness by sweeping transceiver analog settings (for loss profiles beyond nominal cases).
    • Find the optimal RX analog settings with TTK.
    • Apply static values in the QSF file.
1 Intel recommends that you start with Level 0 to evaluate link stability. This setting depends on incoming TX Vpp including link setup. The larger the Vpp, the higher the level of deemphasis setting possible.