JESD204B Intel® FPGA IP Design Example User Guide: Intel® Quartus® Prime Standard Edition

ID 683094
Date 10/31/2022
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

1.7.1.1.3. Core PLL

The core PLL is an Arria 10 I/O PLL (altera_iopll) module that generates the clocks for the FPGA core fabric.
The core PLL uses the device_clk as its reference clock to generate two derivative clocks from a single VCO:
  • Link clock – from output C0
  • Frame clock – from output C1
Table 38.  Clocks
Clock Formula Description
Link Clock Serial data rate/40 The link clock clocks the JESD204B IP core link layer and the link interface of the transport layer.
Frame Clock Serial data rate/(10 × F) The frame clock clocks the transport layer, test pattern generators and checkers, and any downstream modules in the FPGA core fabric.

For the frame clock, when F=1 and F=2, the resulting frame clock value can easily exceed the capability of the core PLL to generate and close timing. The top level RTL file (jesd204b_ed.sv) defines the frame clock division factor parameters, F1_FRAMECLK_DIV (for cases with F = 1) and F2_FRAMECLK_DIV (for cases with F = 2). This factor enables the transport layer and test pattern generator to operate at a divided factor of the required frame clock rate by widening the data width accordingly. For this example design, the F1_FRAMECLK_DIV is set to 4 and F2_FRAMECLK_DIV is set to 2. For example, the actual frame clock for a serial data rate of 6.144 Gbps and F = 1 is:

(6144/(10 × 1)) / F1_FRAMECLK_DIV = 614.4 / 4 = 153.6 MHz