Fishbone H-Clock Tree Construction for Lower Latency and Skew
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Solution Overview
Problem
Existing H-clock trees are incompatible with high-speed interface modules, and suffer from large clock latency and skew, which complicates timing recovery.
Innovation Solution
A fishbone H-clock tree is constructed by introducing intermediate nodes, eliminating redundant nodes, uniformly mounting sinks on TAP nodes, and optimizing metal routing with a shield mechanism, using an EDA tool to adapt to high-speed interface modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional H-clock tree is designed using an EDA tool, then the structure is simple and easy to implement, but the clock latency and skew are large
Solution Approach 1:
The clock tree is segmented into a main trunk and multiple branches extending from TAP nodes. Intermediate nodes are introduced to divide the clock distribution path into smaller segments, allowing each segment to be optimized independently for reduced latency while maintaining the overall H-clock tree structure.
Solution Approach 2:
Intermediate nodes are introduced as intermediary elements between the root node and TAP nodes. These intermediate nodes act as mediators that buffer and redistribute clock signals, reducing the propagation distance and latency while maintaining signal integrity across the clock network.
2Ease of manufacture
If a traditional H-clock tree is designed using an EDA tool, then the structure is simple and easy to implement, but the clock skew is large
Solution Approach 1:
Different regions of the clock tree are assigned different qualities and optimizations. The main trunk uses robust routing for stability, while branches are optimized locally for minimal skew. Each TAP node region is independently optimized to ensure uniform clock arrival times across different parts of the chip.
Solution Approach 2:
The clock tree is designed to achieve equipotentiality in terms of clock arrival times at different TAP nodes. By carefully balancing the path lengths and introducing intermediate nodes, all TAP nodes are brought to approximately the same clock potential, minimizing skew across the entire clock network.
3Manufacturing precision
If an H-clock tree is designed for a module with array-distributed macrocells, then the distances to TAP nodes are equal, but the design is incompatible with high-speed interface modules
Solution Approach 1:
The clock tree design transitions from a static, uniform H-clock structure to a dynamic, adaptable fishbone H-clock tree. The structure can be configured with varying branch lengths and intermediate node placements to accommodate different module types, including high-speed interface modules, while maintaining equal-distance properties where applicable.
Solution Approach 2:
The fishbone H-clock tree structure is designed to be universal and multi-functional, capable of serving both array-distributed macrocell modules and high-speed interface modules. The flexible configuration of intermediate nodes and branches allows the same basic structure to be adapted to different module architectures and speed requirements.
Data Source
AI summary
A method for constructing a fishbone H-clock tree suitable for a high-speed interface module includes the following steps: S1, setting an instance of a clock tree by means of an EDA tool, and eliminating existing definitions; S2, setting a root node, a non-default routing rule and multiple TAP nodes; S3, creating an H-clock tree, and performing H-clock tree synthesis, wherein the H-clock tree synthesis includes: introducing multiple intermediate nodes between the root node and the TAP nodes, editing a clock network between the root node and the TAP nodes by means of an innovus script, and deleting each redundant intermediate node to obtain a structure of a fishbone H-clock tree; mounting multiple sinks on each TAP node, and defining the TAP nodes in a same source group by means of the EDA tool; and performing routing according to the non-default routing rule to complete construction.