Visible to Intel only — GUID: gzu1551318033261
Ixiasoft
1. Intel® Agilex™ General-Purpose I/O and LVDS SERDES Overview
2. Intel® Agilex™ I/O Features and Usage
3. Intel® Agilex™ I/O Termination
4. Intel® Agilex™ High-Speed SERDES I/O Architecture
5. I/O and LVDS SERDES Design Guidelines
6. Troubleshooting Guidelines
7. Documentation Related to the Intel® Agilex™ General-Purpose I/O and LVDS SERDES User Guide
8. Intel® Agilex™ General-Purpose I/O and LVDS SERDES User Guide Archives
9. Document Revision History for the Intel® Agilex™ General-Purpose I/O and LVDS SERDES User Guide
2.2.1. Programmable Output Slew Rate Control
2.2.2. Programmable IOE Delay
2.2.3. Programmable Open-Drain Output
2.2.4. Programmable Bus-Hold
2.2.5. Programmable Pull-Up Resistor
2.2.6. Programmable Pre-emphasis
2.2.7. Programmable De-emphasis
2.2.8. Programmable Differential Output Voltage
2.2.9. Schmitt Trigger Input Buffer
4.1. Intel® Agilex™ High-Speed SERDES I/O Overview
4.2. Using LVDS SERDES Intel FPGA IP for High-Speed LVDS I/O Implementation
4.3. Intel® Agilex™ LVDS SERDES Transmitter
4.4. Intel® Agilex™ LVDS SERDES Receiver
4.5. Intel® Agilex™ LVDS Interface with External PLL Mode
4.6. LVDS SERDES IP Initialization and Reset
4.7. Intel® Agilex™ LVDS SERDES Source-Synchronous Timing Budget
4.8. LVDS SERDES IP Timing
4.9. LVDS SERDES IP Design Examples
5.1.1. VREF Sources and VREF Pins
5.1.2. I/O Standards Implementation based on VCCIO_PIO Voltages
5.1.3. OCT Calibration Block Requirement
5.1.4. Placement Requirements
5.1.5. Simultaneous Switching Noise (SSN)
5.1.6. Special Pins Requirement
5.1.7. External Memory Interface Pin Placement Requirements
5.1.8. HPS Shared I/O Requirements
5.1.9. Clocking Requirements
5.1.10. SDM Shared I/O Requirements
5.1.11. Configuration Pins
5.1.12. Unused Pins
5.1.13. Voltage Setting for Unused I/O Banks
5.1.14. Guidelines for I/O Pins in GPIO, HPS, and SDM Banks During Power Sequencing
5.1.15. Drive Strength Requirement for GPIO Input Pins
5.1.16. Maximum DC Current Restrictions
5.1.17. 1.2 V I/O Interface Voltage Level Compatibility
5.1.18. GPIO Pins for Avalon-ST Configuration Scheme
5.1.19. Maximum True Differential Signaling RX Pairs Per I/O Lane
5.1.20. I/O Simulation
Visible to Intel only — GUID: gzu1551318033261
Ixiasoft
4.7.2. Receiver Skew Margin
Different modes of SERDES receivers use different specifications, which determine the ability to sample the received serial data correctly.
- In non-DPA mode, use RSKM, TCCS, and sampling window (SW) specifications for high-speed source-synchronous differential signals in the receiver data path.
- In DPA and Soft-CDR modes, use DPA jitter tolerance instead of the receiver skew margin (RSKM).
The RSKM equation expresses the relationship between RSKM, TCCS, and SW:
Figure 78. RSKM Equation
The equation uses the following conventions:
- RSKM—the timing margin between the clock input of the receiver and the data input sampling window, and the jitter induced from core noise and I/O switching noise.
- Time unit interval (TUI)—time period of the serial data.
- SW—the period of time that the input data must be stable to ensure that the LVDS receiver samples the data successfully. The SW is a device property and varies according to device speed grade.
- TCCS—the timing difference between the fastest and the slowest output edges across channels driven by the same PLL. The TCCS measurement includes the tCO variation, clock, and clock skew.
Note: If there is additional board channel-to-channel skew, consider the total receiver channel-to-channel skew (RCCS) instead of TCCS. Total RCCS = TCCS + board channel-to-channel skew.
You must calculate the RSKM value, based on the data rate and device, to determine if the LVDS SERDES receiver can sample the data:
- A positive RSKM value, after deducting transmitter jitter, indicates that the LVDS SERDES receiver can sample the data properly.
- A negative RSKM value, after deducting transmitter jitter, indicates that the LVDS SERDES receiver cannot sample the data properly.
Figure 79. Differential High-Speed Timing Diagram and Timing Budget
This example shows the RSKM calculation for Intel® Agilex™ devices at 1 Gbps data rate with a 200 ps board channel-to-channel skew.
- TCCS = 100 ps
- SW = 300 ps
- TUI = 1000 ps
- Total RCCS = TCCS + Board channel-to-channel skew = 100 ps + 200 ps = 300 ps
- RSKM = (TUI – SW – RCCS) / 2 = (1000 ps – 300 ps – 300 ps) / 2 = 200 ps