Custom Logic Device for CPU DisplayPort Signal Re-timing
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Solution Overview
Problem
The lack of a DisplayPort input in some central processing units (CPUs) necessitates the inclusion of an additional Thunderbolt controller in mobile devices, increasing chip count, motherboard size, and cost, as well as restricting the use of integrated Thunderbolt controllers and limiting display output capabilities.
Innovation Solution
A custom chip is used to receive either Thunderbolt or DisplayPort signals from a CPU or GPU, respectively, and re-time them for output over a USB-C port, utilizing Alternate Mode to maximize pin usage and achieve higher transmission speeds, thereby supporting multiple high-resolution displays without the need for an external Thunderbolt chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an additional Thunderbolt controller is included in the motherboard to support DisplayPort input, then display output capability is improved, but chip count and motherboard size increase
Solution Approach 1:
The custom logic device is designed to handle multiple video signal types (Thunderbolt and DisplayPort) through a single interface, making it universal in function. It can receive either TBT or DP signals from the CPU or GPU, re-time them, and output through the USB-C port, thereby supporting display output capability without requiring separate dedicated controllers for each signal type.
Solution Approach 2:
The custom logic device acts as an intermediary between the video signal sources (CPU/GPU) and the USB-C port. It receives video signals from either the CPU's TBT output or the GPU's DP output, processes them through re-timing, and outputs the re-timed signal, thereby mediating the connection and enabling display output without requiring the CPU to have native DP input capability.
2Adaptability or versatility
If an additional Thunderbolt controller is included in the motherboard, then display output capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the functions of Thunderbolt controller and DisplayPort controller into a single custom logic device. This consolidated approach allows the system to support both TBT and DP signals through one component rather than requiring separate controllers, thereby reducing component count, simplifying manufacturing, and lowering overall cost while maintaining display output capability.
3Device complexity
If the integrated Thunderbolt controller is utilized, then chip count is reduced, but display output capability is limited without DP input
Solution Approach 1:
The custom logic device provides dynamic adaptability by being capable of receiving and processing multiple types of video signals (both Thunderbolt and DisplayPort) through a single interface. This dynamic capability allows the system to flexibly handle different signal types without requiring separate static controllers for each, thereby maintaining display output capability while reducing chip count.
Data Source
AI summary
In some examples, a logic device may be connected to: (i) a ThunderBolt (TBT) output of a CPU that lacks a DisplayPort (DP) input and (ii) a DP output of a GPU. The logic device may determine a presence of a video signal, e.g., either: (1) TBT video from the CPU or (2) DP video from the GPU. The logic device may re-time the video signal to create re-timed video and output the re-timed video using a USB-C port. If the logic device determines that the video signal is DP, then the logic device may select a DisplayPort Alternate Mode of the USB-C port and output the re-timed video signal using four differential pairs of the USB-C port. If the logic device determines that the video signal is TBT, then the logic device may output the re-timed video signal using two differential pairs of the USB-C port.