Recirculating Delay Loop and Phase Interpolator for PCB Clock Alignment
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Solution Overview
Problem
Network communication signals, such as SYNC and SYSCLK, often become misaligned due to variations in PCB trace lengths and buffer usage, leading to timing errors.
Innovation Solution
A delay circuit is employed with an input selector, loop delay, and variable delay mechanisms to adjust signal timing, allowing for programmable delay adjustments through recirculation and phase interpolation, ensuring precise alignment of signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different PCB traces and buffers are used for signal transmission, then signal routing flexibility is improved, but timing synchronization deteriorates
Solution Approach 1:
The patent implements variable delay circuits that dynamically adjust signal delay parameters to compensate for timing variations introduced by different PCB traces and buffers. By changing the delay parameter adaptively, the system maintains timing synchronization while allowing routing flexibility.
Solution Approach 2:
The patent employs feedback mechanisms where timing error detectors monitor synchronization status and adjust delay settings accordingly. This closed-loop control ensures that timing synchronization is maintained despite variations in signal paths.
2Measurement precision
If variable delay circuits are added to compensate for timing errors, then timing precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the delay compensation function into multiple independent variable delay circuits, each handling specific signal paths. This segmentation allows for modular implementation and simplifies the overall system architecture while achieving precise timing control.
Solution Approach 2:
The patent designs universal delay circuit blocks that can be applied to multiple signal paths with different routing configurations. This multi-functional approach reduces overall device complexity by reusing the same circuit design across different applications.
3Measurement precision
If recirculating delay loops are used to achieve precise delay control, then delay accuracy is improved, but signal propagation time increases
Solution Approach 1:
The patent implements nested delay structures where fractional delay is achieved by nesting smaller delay units within a larger delay framework. This allows precise delay control through multiple recirculations of shorter delay segments rather than a single long delay, reducing overall propagation time while maintaining accuracy.
Data Source
AI summary
A delay circuit provides a programmable delay and includes an input selector circuit to select between a loop delay output signal and an input signal. A loop delay circuit provides a loop delay to the input signal and supplies the loop delay output signal. The input signal can be recirculated through the loop delay circuit to extend the range of the delay. The input selector circuit selects the feedback signal during recirculation. A variable delay circuit provides a variable delay to the loop delay output signal after the recirculation is complete and supplies a variable delay output signal. An output selector circuit selects the output of the output selector circuit during the recirculation and selects the variable delay output signal after the recirculation is complete to thereby provide a delayed signal with the delay based on the loop delay, the number of loops of recirculation, and the variable delay.