Clocking and PLL User Guide: Agilex™ 3 FPGAs and SoCs

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ID 847921
Date 9/12/2025
Public
Document Table of Contents
Document Table of Contents x
1. Agilex™ 3 Clocking and PLL Overview 2. Agilex™ 3 Clocking and PLL Architecture and Features 3. Agilex™ 3 Clocking and PLL Design Considerations 4. Clock Control Altera™ FPGA IP Core 5. IOPLL FPGA IP 6. I/O PLL Reconfiguration 7. Document Revision History for the Clocking and PLL User Guide: Agilex™ 3 FPGAs and SoCs
1. Agilex™ 3 Clocking and PLL Overview x
1.1. Clock Networks Overview 1.2. PLLs Overview
2. Agilex™ 3 Clocking and PLL Architecture and Features x
2.1. Clock Networks Architecture and Features 2.2. PLLs Architecture and Features
2.1. Clock Networks Architecture and Features x
2.1.1. Clock Network Architecture 2.1.2. Clock Resources 2.1.3. Clock Control Features
2.1.1. Clock Network Architecture x
2.1.1.1. Clock Network Hierarchy 2.1.1.2. Clock Sectors 2.1.1.3. Programmable Clock Routing
2.1.3. Clock Control Features x
2.1.3.1. Clock Gating 2.1.3.2. Clock Divider
2.1.3.1. Clock Gating x
2.1.3.1.1. Root Clock Gate 2.1.3.1.2. Sector Clock Gate 2.1.3.1.3. I/O PLL Clock Gate 2.1.3.1.4. LAB Clock Gate
2.2. PLLs Architecture and Features x
2.2.1. PLL Features 2.2.2. PLL Usage 2.2.3. PLL Locations 2.2.4. PLL Architecture 2.2.5. PLL Control Signals 2.2.6. PLL Feedback Modes 2.2.7. Clock Multiplication and Division 2.2.8. Programmable Phase Shift 2.2.9. Programmable Duty Cycle 2.2.10. PLL Cascading 2.2.11. PLL Input Clock Switchover 2.2.12. PLL Reconfiguration and Dynamic Phase Shift 2.2.13. PLL Calibration
2.2.5. PLL Control Signals x
2.2.5.1. Reset 2.2.5.2. Locked
2.2.6. PLL Feedback Modes x
2.2.6.1. Direct Compensation Mode 2.2.6.2. LVDS Compensation Mode 2.2.6.3. Source Synchronous Compensation Mode 2.2.6.4. Normal Compensation Mode 2.2.6.5. Zero-Delay Buffer Mode 2.2.6.6. External Feedback Mode
2.2.11. PLL Input Clock Switchover x
2.2.11.1. Automatic Switchover 2.2.11.2. Automatic Switchover with Manual Override 2.2.11.3. Manual Clock Switchover
2.2.13. PLL Calibration x
2.2.13.1. Power-Up Calibration 2.2.13.2. User Calibration 2.2.13.3. Static Phase Error Calibration
3. Agilex™ 3 Clocking and PLL Design Considerations x
3.1. Guidelines: Clock Switchover 3.2. Guidelines: Timing Closure 3.3. Guidelines: Resetting the PLL 3.4. Guidelines: Configuration Constraints 3.5. Clocking Constraints 3.6. IP Constraints 3.7. Guideline: Achieving 5% Duty Cycle for fOUT_EXT ≥ 300 MHz Using tx_outclk Port from LVDS SERDES IP
4. Clock Control Altera™ FPGA IP Core x
4.1. Release Information for Clock Control Altera™ FPGA IP 4.2. Clock Control Altera™ FPGA IP Parameters 4.3. Clock Control Altera™ FPGA IP Ports and Signals
5. IOPLL FPGA IP x
5.1. Release Information for IOPLL FPGA IP 5.2. IOPLL FPGA IP Parameters 5.3. IOPLL IP Ports and Signals
5.2. IOPLL FPGA IP Parameters x
5.2.1. IOPLL IP Parameters - PLL Tab 5.2.2. IOPLL IP Parameters - Settings Tab 5.2.3. IOPLL IP Parameters - Cascading Tab 5.2.4. IOPLL IP Parameters - Advanced Parameters Tab
6. I/O PLL Reconfiguration x
6.1. Implementing HSIO I/O PLL Reconfiguration using EMIF Calibration IP 6.2. Implementing HVIO I/O PLL Reconfiguration 6.3. Address Bus and Data Bus Settings
6.1. Implementing HSIO I/O PLL Reconfiguration using EMIF Calibration IP x
6.1.1. Release Information for EMIF Calibration IP 6.1.2. Setting Up the IOPLL FPGA IP 6.1.3. Setting Up the EMIF Calibration IP 6.1.4. Connectivity Between IOPLL FPGA IP and EMIF Calibration IP 6.1.5. Axilite Interface Ports in the EMIF Calibration IP 6.1.6. Reconfiguration Guideline for HSIO I/O PLLs 6.1.7. Design Example for HSIO I/O PLL Reconfiguration
6.1.6. Reconfiguration Guideline for HSIO I/O PLLs x
6.1.6.1. Enabling Reconfiguration for The Desired I/O PLL 6.1.6.2. Clearing off Calibration Statuses 6.1.6.3. Reconfiguring The I/O PLL 6.1.6.4. Recalibration of I/O PLL 6.1.6.5. Clock Gating (Optional)
6.1.7. Design Example for HSIO I/O PLL Reconfiguration x
6.1.7.1. Reconfiguration Option: Reconfiguration Through EMIF Calibration IP 6.1.7.2. Reconfiguration Option: Clock Gating Reconfiguration
6.2. Implementing HVIO I/O PLL Reconfiguration x
6.2.1. Setting Up the IOPLL FPGA IP 6.2.2. Reconfiguration Guideline for HVIO I/O PLLs 6.2.3. Design Example for HVIO I/O PLL Reconfiguration
6.2.2. Reconfiguration Guideline for HVIO I/O PLLs x
6.2.2.1. Read and Write Operations via Avalon® Memory-Mapped Interface 6.2.2.2. Enabling Reconfiguration for The Desired I/O PLL 6.2.2.3. Clearing off Calibration Statuses 6.2.2.4. Reconfiguring The I/O PLL 6.2.2.5. Enabling Recalibration for HVIO PLLs 6.2.2.6. Requesting Recalibration of I/O PLL 6.2.2.7. Clock Gating (Optional)
6.2.3. Design Example for HVIO I/O PLL Reconfiguration x
6.2.3.1. Reconfiguration Option: Reconfiguration Through EMIF Calibration IP 6.2.3.2. Reconfiguration Option: Clock Gating Reconfiguration
6.3. Address Bus and Data Bus Settings x
6.3.1. Divide Settings and the Corresponding Data Bit Setting for Reconfiguration 6.3.2. Data Bus Setting for Clock Gating Reconfiguration 6.3.3. Data Bus Setting For Charge Pump Current
1. Agilex™ 3 Clocking and PLL Overview
2. Agilex™ 3 Clocking and PLL Architecture and Features
3. Agilex™ 3 Clocking and PLL Design Considerations
4. Clock Control Altera™ FPGA IP Core
5. IOPLL FPGA IP
6. I/O PLL Reconfiguration
7. Document Revision History for the Clocking and PLL User Guide: Agilex™ 3 FPGAs and SoCs

2.2.6.6. External Feedback Mode

In external feedback (EFB) mode, the output of the M counter (fbout) feeds back to the PLL fbin input (using a trace on the board) and becomes part of the feedback loop. EFB mode is only supported for I/O bank I/O PLL, not supported for fabric-feeding I/O PLL.

One of the dual-purpose external clock outputs becomes the fbin input pin in this mode. The external feedback input pin, fbin is phase-aligned with the clock input pin. Aligning these clocks allows you to remove clock delay and skew between devices.

In EFB mode, you must use the same I/O standard on the input clock, feedback input, and clock outputs.

Figure 17. Example of Phase Relationship Between the PLL Clocks in EFB Mode


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