By PURPLELEC | 18 December 2024 | 0 Comments
DisplayPort 2.1 Specification Overview
The DisplayPort 2.1 specification is the latest standard from VESA (Video Electronics Standards Association), officially released on October 17, 2022. This specification maintains full backward compatibility with all previous versions and introduces several important updates. This article will explore the protocol and encoding changes, new link rates, and cable design of DisplayPort 2.1 in detail.
Protocol and Encoding Changes
DisplayPort 1.4 and earlier versions used 8b/10b encoding, which had a data overhead of up to 20%, meaning that 20% of the transmitted data was unrelated to the displayed image and was discarded. To improve efficiency, DisplayPort 2.0/2.1 introduces the 128b/132b encoding method, reducing the data overhead to just 3%, allowing for the transmission of more display-related data.
Moreover, the introduction of 128b/132b encoding enables DisplayPort 2.1 to align with other cutting-edge technologies such as USB4, Thunderbolt 3/4, and PCI Express 3.0-5.0, facilitating IC designers to utilize existing IC components and technologies in their designs and implementations.
New Link Rates
Compared to DisplayPort 1.4, DisplayPort 2.1 achieves a significant increase in data rates, making higher resolutions and refresh rates possible. Specifically, the maximum single display output for DisplayPort 1.4 is 8K (7680 x 4320) at 30Hz and 24 bpp 4:4:4 (uncompressed), while DisplayPort 2.1 supports 10K (10240×4320) at 60Hz and 24 bpp 4:4:4 (uncompressed) displays.
In terms of link rates, DisplayPort 2.1 devices must support a link rate of 10 Gbps per channel, with support for 13.5 Gbps and 20 Gbps per channel being optional. Additionally, DisplayPort 2.1 exclusively uses multi-stream transport (MST) encoding, applying the same pixel data to DP link symbol mapping whether connecting to one or multiple displays.
Cable Design
Cables, as the critical connection between the DisplayPort source and receiver, become increasingly important as link rates rise. The DisplayPort 2.1 specification categorizes cables into four types: DP80, DP40, DP8K, and HBR, and introduces new enhanced full-size DP and mDP connectors.
To support higher link rates, DP80 and DP40 cables must support link rates of UHBR20, UHBR13.5 and below, and UHBR10, respectively. These cables use the same enhanced connectors as DP80 and allow for longer cable designs while meeting the same mechanical requirements. Furthermore, all new DP cables must be backward compatible with existing DP 1.2/1.4 source and receiver devices.
Regarding connectors, the enhanced full-size DP connectors come in Type 1 and Type 2, supporting up to 4 channels of UHBR13.5 and UHBR20, respectively. These connectors utilize mandatory paddle cards (PCBs) to ensure signal quality meets requirements, and the increased shielding and pin layout necessitate more PCBA space.
Conclusion
In summary, the DisplayPort 2.1 specification lays a solid foundation for supporting future ultra-high-resolution displays through updated link speeds, the introduction of new 128b/132b encoding, and enhanced connector designs. Additionally, support for the MST standard enables high-resolution multi-output devices across multiple operating systems. With these new capabilities, DisplayPort will continue to maintain its market leadership in the PC industry for many years to come.
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