LVDS SERDES User Guide: Agilex™ 5 FPGAs and SoCs

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ID 813929
Date 8/11/2025
Public
Document Table of Contents
Document Table of Contents x
1. Agilex™ 5 LVDS SERDES Overview 2. Agilex™ 5 LVDS SERDES Architecture 3. Agilex™ 5 LVDS SERDES Transmitter 4. Agilex™ 5 LVDS SERDES Receiver 5. Agilex™ 5 High-Speed LVDS I/O Implementation Guide 6. Agilex™ 5 LVDS SERDES Timing 7. LVDS SERDES FPGA IP Design Examples 8. Agilex™ 5 LVDS SERDES Design Guidelines 9. Agilex™ 5 LVDS SERDES Troubleshooting Guidelines 10. LVDS SERDES User Guide: Agilex™ 5 FPGAs and SoCs Archives 11. Document Revision History for the LVDS SERDES User Guide: Agilex™ 5 FPGAs and SoCs
1. Agilex™ 5 LVDS SERDES Overview x
1.1. LVDS SERDES Usage Modes
2. Agilex™ 5 LVDS SERDES Architecture x
2.1. Agilex™ 5 HSIO Banks, SERDES, and DPA Locations 2.2. SERDES Blocks, Modes, and Clock Domains
3. Agilex™ 5 LVDS SERDES Transmitter x
3.1. LVDS SERDES Transmitter Blocks 3.2. Serializer 3.3. Clocking the Differential Transmitters
3.2. Serializer x
3.2.1. Serializer Bypass for DDR and SDR Operations 3.2.2. Differential I/O Bit Position
3.3. Clocking the Differential Transmitters x
3.3.1. Transmitter Output Clock Parameters Settings
3.3.1. Transmitter Output Clock Parameters Settings x
3.3.1.1. Edge-Aligned tx_outclock to tx_out 3.3.1.2. Center-Aligned tx_outclock to tx_out
4. Agilex™ 5 LVDS SERDES Receiver x
4.1. LVDS SERDES Receiver Blocks 4.2. Clocking the LVDS SERDES Receivers 4.3. LVDS SERDES Receiver Modes
4.1. LVDS SERDES Receiver Blocks x
4.1.1. Dynamic Phase Alignment Block 4.1.2. Synchronizer (DPA FIFO) 4.1.3. Data Realignment Block (Bit Slip) 4.1.4. Deserializer
4.2. Clocking the LVDS SERDES Receivers x
4.2.1. Receiver Input Clock Parameters Settings for Non-DPA Mode
4.2.1. Receiver Input Clock Parameters Settings for Non-DPA Mode x
4.2.1.1. Edge-Aligned inclock to rx_in 4.2.1.2. Center-Aligned inclock to rx_in
4.3. LVDS SERDES Receiver Modes x
4.3.1. Non-DPA Mode 4.3.2. DPA Mode 4.3.3. Soft-CDR Mode
5. Agilex™ 5 High-Speed LVDS I/O Implementation Guide x
5.1. LVDS SERDES FPGA IP 5.2. LVDS Interface with External PLL Mode 5.3. LVDS SERDES IP Initialization and Reset
5.1. LVDS SERDES FPGA IP x
5.1.1. Release Information 5.1.2. LVDS SERDES FPGA IP Features 5.1.3. LVDS SERDES IP Usage Modes 5.1.4. Planning the LVDS SERDES Interface 5.1.5. Generating the LVDS SERDES FPGA IP 5.1.6. LVDS SERDES FPGA IP Parameter Settings 5.1.7. LVDS SERDES FPGA IP Signals
5.1.5. Generating the LVDS SERDES FPGA IP x
5.1.5.1. Altera® FPGA IP Generation Output
5.1.6. LVDS SERDES FPGA IP Parameter Settings x
5.1.6.1. LVDS SERDES FPGA IP General Settings 5.1.6.2. LVDS SERDES FPGA IP Pin Settings 5.1.6.3. LVDS SERDES FPGA IP PLL Settings 5.1.6.4. LVDS SERDES FPGA IP Receiver Settings 5.1.6.5. LVDS SERDES FPGA IP Transmitter Settings 5.1.6.6. LVDS SERDES FPGA IP Clock Resource Summary
5.1.6.2. LVDS SERDES FPGA IP Pin Settings x
5.1.6.2.1. HSIO Pin Index Number and Respective Channel Pin Selection 5.1.6.2.2. Placing Channel Bytes in I/O Lanes 5.1.6.2.3. Locating the I/O Lane and Channel Pin through the Interface Planner
5.2. LVDS Interface with External PLL Mode x
5.2.1. IOPLL IP Signal Interface with LVDS SERDES IP 5.2.2. IOPLL Parameter Values for External PLL Mode 5.2.3. Connection between IOPLL IP and LVDS SERDES IP in External PLL Mode
5.3. LVDS SERDES IP Initialization and Reset x
5.3.1. Initializing the LVDS SERDES IP in Non-DPA Mode 5.3.2. Initializing the LVDS SERDES IP in DPA Mode 5.3.3. Resetting the DPA 5.3.4. Word Boundaries Alignment
5.3.4. Word Boundaries Alignment x
5.3.4.1. Aligning Word Boundaries
6. Agilex™ 5 LVDS SERDES Timing x
6.1. LVDS SERDES FPGA IP Timing 6.2. LVDS SERDES Source-Synchronous Timing Budget
6.1. LVDS SERDES FPGA IP Timing x
6.1.1. I/O Timing Analysis 6.1.2. FPGA Timing Analysis 6.1.3. Timing Analysis for the External PLL Mode
6.1.1. I/O Timing Analysis x
6.1.1.1. Obtaining RSKM Report 6.1.1.2. Obtaining TCCS Report
6.2. LVDS SERDES Source-Synchronous Timing Budget x
6.2.1. Transmitter Channel-to-Channel Skew 6.2.2. Receiver Skew Margin RSKM Calculation Example
7. LVDS SERDES FPGA IP Design Examples x
7.1. LVDS SERDES IP Synthesizable Quartus® Prime Design Examples 7.2. LVDS SERDES IP Simulation Design Example
8. Agilex™ 5 LVDS SERDES Design Guidelines x
8.1. Use PLLs in Integer PLL Mode for LVDS SERDES 8.2. Use High-Speed Clock from PLL to Clock SERDES Only 8.3. Pin Placement for Differential Channels 8.4. SERDES Pin Pairs for Soft-CDR Mode 8.5. Placing LVDS SERDES Transmitters and Receivers with External PLL 8.6. Sharing LVDS SERDES I/O Lane with Other IPs
8.3. Pin Placement for Differential Channels x
8.3.1. I/O PLLs Driving LVDS SERDES Transmitter and Receiver Channels 8.3.2. Placement Restrictions for True Differential and Single-Ended I/O Standards in the Same or Adjacent HSIO Bank
1. Agilex™ 5 LVDS SERDES Overview
2. Agilex™ 5 LVDS SERDES Architecture
3. Agilex™ 5 LVDS SERDES Transmitter
4. Agilex™ 5 LVDS SERDES Receiver
5. Agilex™ 5 High-Speed LVDS I/O Implementation Guide
6. Agilex™ 5 LVDS SERDES Timing
7. LVDS SERDES FPGA IP Design Examples
8. Agilex™ 5 LVDS SERDES Design Guidelines
9. Agilex™ 5 LVDS SERDES Troubleshooting Guidelines
10. LVDS SERDES User Guide: Agilex™ 5 FPGAs and SoCs Archives
11. Document Revision History for the LVDS SERDES User Guide: Agilex™ 5 FPGAs and SoCs

6.2.2. Receiver Skew Margin

Different modes of SERDES receivers use different specifications, which determine the ability to sample the received serial data correctly.
  • In the non-DPA mode, use RSKM, TCCS, and sampling window (SW) specifications for high-speed source-synchronous differential signals in the receiver data path.
  • In the DPA and Soft-CDR modes, use DPA jitter tolerance instead of the receiver skew margin (RSKM).
Equation 2. RSKM EquationThis equation expresses the relationship between RSKM, TCCS, and SW.

Table 37.  RSKM Equation Conventions
Symbol Description
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) The time period of the serial data.
SW The period of time that the input data must be stable to ensure that the LVDS SERDES 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. .

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 34. Differential High-Speed Timing Diagram and Timing Budget

RSKM Calculation Example

This example shows the RSKM calculation for Agilex™ 5 devices at 1 Gbps data rate with a 200 ps board channel-to-channel skew.

Equation 3. RSKM Calculation

The non-DPA receiver works correctly if the RSKM is greater than 0 ps after deducting transmitter jitter.

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