Clock Tree Delay Routing for Higher-Frequency Integrated Circuits
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Solution Overview
Problem
Conventional integrated circuit designs face challenges in managing clock skew, which affects the performance of sequential logic circuits by limiting the maximum frequency and increasing the area and cost of the circuit due to the linear growth of programmable delay elements with the number of registers.
Innovation Solution
The implementation of a circuit with programmable interconnect elements and delay elements in the clock tree, allowing for selective placement of delays along the clocking resources rather than at the clock pins of destination registers, enabling time borrowing and reducing area and power overheads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If programmable delay elements are introduced before the clock pin of each destination register to correct clock skew, then the clock skew is reduced and sequential logic performance is improved, but the area required for implementing the delay grows linearly with the number of registers, significantly increasing the cost of the integrated circuit device
Solution Approach 1:
The patent segments the clock distribution network into multiple clock trees, each serving a specific region or group of registers. By dividing the overall clock distribution function into smaller segments, the need for delay elements at every register is eliminated, as each clock tree can be independently optimized to provide appropriate skew compensation for its region without requiring individual delay elements at each destination.
Solution Approach 2:
The patent introduces clock trees as intermediary structures between the clock source and destination registers. These clock trees act as mediators that distribute clock signals with controlled skew characteristics, eliminating the need for delay elements at each register while still providing the necessary skew compensation. The clock tree structure serves as an intermediate layer that manages timing relationships across multiple registers simultaneously.
2Productivity
If delay elements are placed at each clock pin to achieve precise timing control, then the maximum frequency (Fmax) can be improved, but the power consumption and area overhead increase significantly
Solution Approach 1:
The patent merges the delay functionality into the clock tree structure itself rather than using separate delay elements at each register. The clock tree is designed with inherent delay characteristics through its routing topology and buffering structure, combining clock distribution and skew compensation into a single integrated system. This eliminates the need for additional power-consuming delay elements at each destination while maintaining the ability to achieve precise timing control for maximizing Fmax.
3Area of stationary object
If conventional clock distribution is used without programmable delays, then the area and power consumption are minimized, but the clock skew limits the performance of sequential logic circuits and reduces the maximum operating frequency
Solution Approach 1:
The patent implements dynamically adjustable clock trees that can be configured to optimize skew compensation for different operating conditions and circuit configurations. The clock tree structure includes programmable elements that allow the timing characteristics to be adjusted dynamically, enabling the system to achieve optimal Fmax performance without requiring static delay elements at every register. This dynamic configuration capability allows the same clock tree to serve multiple timing requirements across different regions and operating modes.
Data Source
AI summary
A circuit for routing signals in an integrated circuit is disclosed. The circuit comprises a path having a plurality of registers coupled in series and including a source register, a destination register and at least one intermediate register; a clock generator generating a clock signal; and a delay element coupled to receive the clock signal and generate a delayed clock signal, wherein the delayed clock signal is coupled to a clock input of the at least one intermediate register. A method of routing signals in an integrated circuit is also disclosed.