Clock Routing Circuit for Dynamic Lane-to-Lane Skew Compensation
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Solution Overview
Problem
Modern integrated circuits face challenges in reducing lane-to-lane clock skew, which leads to desynchronization of data transmission across multiple lanes, particularly in high-bandwidth applications like PCIe and HBM, where tight timing requirements are not met due to varying clock signal delays.
Innovation Solution
A dynamic lane-to-lane skew reduction technique is implemented using a clocking architecture with first and second delayed clock signals routed through multiple traces, processed by skew compensation circuits to generate a user clock signal with consistent delay relative to a reference clock, thereby reducing lane-to-lane skew dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If clock signals are routed through multiple lanes in traditional architectures, then data transmission can occur across parallel lanes, but lane-to-lane clock skew increases causing desynchronization
Solution Approach 1:
Instead of routing clock signals in the traditional forward direction through each lane sequentially, the patent routes clock signals in opposite directions through first and second pluralities of routing traces. This inverted approach allows skew compensation by equalizing the total delay experienced by clock signals across different lanes, thereby reducing lane-to-lane skew while maintaining high bandwidth capability
Solution Approach 2:
The patent dynamically adjusts delay parameters by introducing variable delay elements in the clock routing paths. By changing the delay parameters of individual routing traces based on measured skew conditions, the system optimizes clock synchronization across lanes while maintaining high data transmission bandwidth
2Manufacturing precision
If skew compensation is performed manually during place and route stage, then clock skew can be balanced, but design cycle time increases
Solution Approach 1:
The system performs self-service by automatically measuring and compensating for clock skew during runtime using the dynamic skew compensation circuitry. This eliminates the need for manual skew balancing during the place and route stage, significantly reducing design cycle time while maintaining precise clock synchronization across lanes
3Manufacturing precision
If dynamic skew compensation circuitry is added, then lane-to-lane skew is reduced, but circuit complexity increases
Solution Approach 1:
The skew compensation system is segmented into modular components including separate delay measurement circuits, delay adjustment elements, and control logic for each lane group. This segmentation allows independent optimization of each segment and simplifies the overall design by breaking down the complex skew compensation function into manageable, reusable modules
Data Source
AI summary
Apparatus and associated methods relate to a dynamic lane-to-lane skew reduction technique having (a) a clocking architecture configured to provide a corresponding first delayed clock signal and a corresponding second delayed clock signal through a first and a second plurality of routing traces, respectively, and (b) a number of skew compensation circuits configured to process the corresponding first delayed clock signal and the corresponding second delayed clock signal to generate a corresponding user clock signal for a corresponding lane of a transmitter. In an illustrative example, a first routing trace may transmit a first delayed clock signal in a direction opposite to a second routing trace transmitting a second delayed clock signal. By implementing the technique, each transmitter lane may receive a corresponding user clock signal having substantially the same delay relative to a reference clock signal such that dynamic lane-to-lane skew may be advantageously reduced.