Clock Grid Switching and Deskewing for Low-Skew IC Domains
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Solution Overview
Problem
As integrated circuits increase in size and speed, the distribution of clock signals becomes challenging due to increased metallization resources and decreased acceptable clock skew, particularly with the limitations of traditional H-tree networks, which struggle to manage high-speed serial interfaces and multiple clock domains.
Innovation Solution
The implementation of a switch box and distributed deskew objects within a clock grid network that allows for selectable and deskewed clock signals to be distributed efficiently across the integrated circuit, enabling low-skew clock domains of arbitrary shapes and sizes, and allowing for post-manufacturing creation of custom clock regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If H-tree clock network is used to distribute clock signals, then clock skew is reduced, but metallization resources increase dramatically
Solution Approach 1:
The clock distribution network is segmented into multiple independent H-tree networks, each serving a specific clock domain. This allows clock signals to be distributed with reduced skew within each domain while avoiding the need for a single comprehensive H-tree that would consume excessive metallization resources across the entire device.
Solution Approach 2:
Each clock domain receives a dedicated clock signal optimized for its specific requirements and spatial location. The clock distribution is tailored to local needs rather than using a uniform approach, reducing the overall metallization burden while maintaining low skew within each domain.
2Area of stationary object
If device size increases, then more clock domains are needed, but acceptable clock skew margin decreases
Solution Approach 1:
The large device is divided into multiple smaller clock domains, each with its own H-tree network. This segmentation ensures that the maximum distance from the clock source to any destination within a domain remains limited, thereby maintaining acceptable skew margins even as the overall device size increases.
Solution Approach 2:
Clock domain isolation mechanisms act as intermediaries between different clock domains, preventing skew in one domain from affecting others. This allows each domain to be optimized independently for low skew while accommodating the overall large device footprint.
3Adaptability or versatility
If multiple clock domains are distributed throughout the device, then high-speed serial interfaces are supported, but device complexity increases
Solution Approach 1:
Each clock domain is designed with a standardized H-tree structure that can serve multiple functions - supporting various high-speed serial interfaces and different clock frequencies. This universal approach reduces complexity by using the same basic building block for different purposes rather than designing custom distribution networks for each interface type.
Data Source
AI summary
Systems and methods are provided for distributing clocks or other signals on an integrated circuit. In some aspects, one ore more distributed deskewing objects are provisioned for reducing or eliminating skew while linking multiple clock distribution segments into one clock tree of an arbitrary shape and size.