F-Tile SDI II Intel® FPGA IP Design Example User Guide

ID 710496
Date 7/08/2024
Public

2.3.2.1. Clocking Scheme Components

Table 11.  Clocking Scheme Components
Diagram Label Description
TX PLL refclock 8

TX PLL reference clock which can be any clock frequency that is divisible by transceiver for that data rate. This clock must be connected from a dedicated transceiver reference clock pin to the input clock port of Reference and System PLL Clocks IP, before connecting the corresponding output port to SDI top module.

  • Parallel loopback with external VCXO
    • Due to the limitation on Nextera daughter card which only has 297 MHz, this design example has the TX PLL reference clock connected to the 297 MHz clock.
    • Use a minimum clock frequency of 148.5 MHz to meet jitter performance specification.
  • Parallel loopback without external VCXO
    • Use 141 MHz to meet jitter performance specification.
  • Serial loopback
    • For this design, the TX PLL refclock is configured to generate clock for integer frame rate.
    • Use a minimum clock frequency of 148.5 MHz to meet jitter performance specification.
TX PLL alt refclock Second TX PLL reference clock can be any clock frequency that is divisible by transceiver for that data rate. This clock must be connected from a dedicated transceiver reference clock pin to the input clock port of Reference and System PLL Clocks IP, before connecting the corresponding output port to SDI top module.
  • Serial loopback
    • For this design example, TX PLL alt refclock is configured to generate clock for fractional frame rate. To meet the jitter specification, Intel recommends using 148.35 MHz as the reference clock frequency.
RX CDR refclock 8

Transceiver clock data recovery (CDR) reference clock, of any frequency divisible by the transceiver for that data rate. Only a single reference clock frequency which the recommendation is 148.5 MHz is required to support both integer and fractional frame rate. It must be a free running clock connected from a dedicated transceiver reference clock pin to the input clock port of Reference and System PLL Clocks IP, before connecting the corresponding output port to SDI top module.

SysPLL refclock

F-Tile System PLL reference clock, of any frequency divisible by System PLL for that output frequency. It must be a free running clock connected from a dedicated transceiver reference clock pin to the input clock port of Reference and System PLL Clocks IP, before connecting the corresponding output port to SDI top module.

Note: For this demonstration, the System PLL clock output is set to the maximum supported frequency of 900 MHz. For your design, select a frequency that can support all the components that share the same PLL output. For example, set the output frequency to 891 MHz if no other component requires more than such frequency. This would allow 148.5 MHz as a refclock frequency option and enable you to share the same refclock pin as TX PLL refclock or RX CDR refclock to reduce the number of refclocks required.
GPIO clock / RX coreclk / DR clocks

SDI RX core reference clock which must be a free running clock depending on the RX core clock Frequency parameter value. Intel recommends that you use the same clock source for rx/tx_rcfg_mgmt_clk as well as the clock to DR arbiter and DR IP.

All generated design examples have this clock set to 148.5 MHz regardless of the GUI option because of the development kit's default limited clock frequency option.
TX PLL / RX CDR link clock

Output ports from Reference and System PLL Clocks IP. These clocks must be connected to the transceiver reference clock input of F-Tile Direct PHY IP.

System PLL output link clock

Output ports from Reference and System PLL Clocks IP. These clocks must be connected to the system PLL clock input of F-Tile Direct PHY IP.

The minimum System PLL output frequency for each SDI mode is given below:
SDI Mode Minimum System PLL Output Frequency
HD-SDI single rate 150 MHz
3G-SDI single rate 300 MHz
Triple-rate SDI (up to 3G-SDI) 300 MHz
Multi-rate SDI (up to 12G-SDI) 600 MHz
TX/RX transceiver clkout2

Recovered clock from transceiver.

For SD video standard:

  • 148.5 MHz

For HD video standard:

  • 74.25 MHz when receiving integer frame rate.
  • 74.1758 MHz when receiving fractional frame rate

For 3G/6G/12G video standard:

  • 148.5 MHz when receiving integer frame rate.
  • 148.35 MHz when receiving fractional frame rate
TX/RX transceiver clkout This is the div2 clock from System PLL output clock which the F-Tile PMA/FEC Direct PHY IP is operating in. This clock must be connected to a DCFIFO which serves as the interface between SDI II IP and the Direct PHY IP.
AXIS clock Clock for AXI4-Stream video. Clock frequency must be greater than 297 MHz. This clock is only available when you select AXIS-VVP Full active video data protocols.
8 Intel recommends you not to share TX PLL reference clock with RX transceiver reference clock for a parallel loopback design because TX PLL clock is going to be tuned to match RX recovered clock frequency.