Agilex™ 7 Clocking and PLL User Guide: F-Series and I-Series

ID 683761
Date 4/01/2024
Document Table of Contents

2.2.13. PLL Calibration

I/O PLLs include both analog and digital blocks that require calibration to compensate for process, voltage, and temperature (PVT) variations. F-Series and I-Series uses the I/O manager to perform calibration routines.

There are two main types of calibration.

  • Power-up calibration—initiates automatically at device power-up and runs during device configuration.
  • User calibration—if you perform dynamic reconfiguration or change the reference clock frequency of the I/O PLL, you must perform user recalibration. You must enable the required calibration sequence.

To successfully complete the calibration process, OSC_CLK_1 clocks and all reference clocks driving the I/O PLLs must be stable and free running at the start of FPGA configuration. If clock switchover is enabled, both reference clocks must be present for calibration. During user mode, when the I/O PLL does not detect a reference clock during configuration, calibration attempts continue periodically. After calibration has completed, the I/O PLL is locked automatically.