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1. Agilex™ 5 Clocking and PLL Overview
2. Agilex™ 5 Clocking and PLL Architecture and Features
3. Agilex™ 5 Clocking and PLL Design Considerations
4. Clock Control Intel® FPGA IP Core
5. IOPLL Intel® FPGA IP Core
6. Document Revision History for the Clocking and PLL User Guide: Agilex™ 5 FPGAs and SoCs
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
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 Core Constraints
3.7. Guideline: Achieving 5% Duty Cycle for fOUT_EXT ≥ 300 MHz Using tx_outclk Port from LVDS SERDES Intel® FPGA IP
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2.2.10. PLL Cascading
Agilex™ 5 devices support PLL-to-PLL cascading. You can cascade a maximum of two PLLs. PLL cascading synthesizes more output clock frequencies than a single PLL.
Agilex™ 5 devices support the following PLL-to-PLL cascading modes for I/O bank I/O PLL and I/O Bank Fabric-Feeding I/O PLL. HVIO fabric-feeding I/O PLL do not support cascading.
- I/O Bank I/O-PLL-to-I/O Bank I/O-PLL cascading
- I/O Bank I/O-PLL-to-I/O Bank fabric-feeding I/O-PLL cascading
- I/O Bank fabric-feeding I/O-PLL-to I/O Bank I/O-PLL cascading
Cascading of PLLs can be done via two paths: via dedicated cascade path or via core clock fabric.
- Cascading via dedicated cascade path—upstream I/O PLL and downstream I/O PLL must be in the same I/O column and are placed adjacently.
- Cascading via core clock fabric—no restriction on locations of upstream and downstream I/O PLL.
The permit_cal input of the downstream I/O PLL must be connected to the locked output of the upstream I/O PLL in both PLL cascading modes.
The following figures show the connectivity required between the upstream and downstream I/O PLL for both the PLL cascading modes.
Figure 18. I/O-PLL-to-I/O-PLL Cascading Through Dedicated Cascade Path
Figure 19. I/O-PLL-to-I/O-PLL Cascading Through Core Clock Fabric