HDMI Intel® FPGA IP User Guide

ID 683798
Date 4/22/2022
Public

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4.3.1.2. PLL Intel FPGA IP Cores

Use the PLL Intel FPGA IP core as the HDMI PLL to generate reference clock for RX or TX transceiver, link speed, and video clocks for the HDMI RX or TX IP core.

The HDMI PLL is referenced by the arbitrary TMDS clock. For HDMI source, you can reference the HDMI PLL by a separate clock source in the VIP passthrough design, which contains frame buffer. The HDMI PLL for TX has the same desired output frequencies as RX across symbols per clock and color depth.

  • For TMDS bit rates ranging from 3,400 Mbps to 6,000 Mbps (HDMI 2.0), the TMDS clock rate is 1/40 of the TMDS bit rate. The HDMI PLL generates reference clock for RX/TX transceiver at 4 times the TMDS clock.
  • For TMDS bit rates below 3,400 Mbps (HDMI 1.4b), the TMDS clock rate is 1/10 of the TMDS bit rate. The HDMI PLL generates reference clock for RX/TX transceiver at identical rate as the TMDS clock.
If the TMDS link operates at TMDS bit rates below the minimum RX/TX transceiver link rate, your design requires oversampling and a factor of 5 is chosen. The minimum link rate of the RX/TX transceiver vary across device families and symbols per clock. The HDMI PLL generates reference clock for RX/TX transceiver at 5 times the TMDS clock.
Note: Place the PLL Intel FPGA block on the transmit path (pll_hdmi_tx) in the physical location next to the transceiver PLL.
Table 14.  HDMI PLL Desired Output Frequencies for 8-bpc VideoThis table shows an example of HDMI PLL desired output frequencies across various TMDS clock rates and symbols per clock for all supported device families using 8-bpc video.
Device Family Symbols Per Clock Minimum Link Rate (Mbps) TMDS Bit Rate (Mbps) Oversampling (5x) Required TMDS Clock Rate (MHz) RX/TX Transceiver Refclk (MHz) RX/TX Link Speed Clock (MHz) RX/TX Video Clock (MHz)
Arria V 2 611 270 Yes 27 135 13.5 13.5
742.5 No 74.25 74.25 37.125 37.125
1,485 No 148.5 148.5 74.25 74.25
2,970 No 297 297 148.5 148.5
4 1,000 270 Yes 27 135 6.75 6.75
742.5 Yes 74.25 371.25 18.5625 18.5625
1,485 No 148.5 148.5 37.125 37.125
5,940 No 148.5 594 148.5 148.5
Stratix V 2 611 540 Yes 54 270 27 27
1,620 No 162 162 81 81
5,934 No 148.35 593.4 296.7 296.7

The color depths greater than 8 bpc or 24 bpp are defined to be deep color. For a color depth of 8 bpc, the core carries the pixels at a rate of one pixel per TMDS clock. At deeper color depths, the TMDS clock runs faster than the source pixel clock to provide the extra bandwidth for the additional bits.

The TMDS clock rate is increased by the ratio of the pixel size to 8 bits:

  • 8 bits mode—TMDS clock = 1.0 × pixel or video clock (1:1)
  • 10 bits mode—TMDS clock = 1.25 × pixel or video clock (5:4)
  • 12 bits mode—TMDS clock = 1.5 × pixel or video clock (3:2)
  • 16 bits mode—TMDS clock = 2 × pixel or video clock (2:1)
Table 15.  HDMI PLL Desired Output Frequencies for Deep Color VideoThis table shows an example of HDMI PLL desired output frequencies across symbols per clock and color depths.
Symbols Per Clock Oversampling (5x) Required Bits Per Component TMDS Bit Rate (Mbps) 5 TMDS Clock Rate (MHz) RX/TX Transceiver Refclk (MHz) RX/TX Link Speed Clock (MHz) RX/TX Video Clock (MHz)
2 Yes 8 270 27 135 13.5 13.5
10 6 337.5 33.75 168.75 16.875 13.5
12 6 405 40.5 202.5 20.25 13.5
16 6 540 54 270 27 13.5
4 No 8 1,485 148.5 148.5 37.125 37.125
10 6 1,856.25 185.625 185.625 46.40625 37.125
12 6 2,227.5 222.75 222.75 55.6875 37.125
16 6 2,970 297 297 74.25 37.125
The default frequency setting of the HDMI PLL is fixed at possible maximum value for each clock for appropriate timing analysis.
Note: This default combination is not valid for any HDMI resolution. The core will reconfigure to the appropriate settings upon power up.
5 The TMDS bit rate is 10x the TMDS character rate. For information about how the TMDS character rate is derived from the pixel clock rate, refer to the HDMI Specifications.
6 For this release, deep color video is only demonstrated in VIP bypass mode. It is not available in VIP passthrough mode.

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