Clock Duty-Cycle Correction With Matched Delay Clock Trees
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Solution Overview
Problem
Existing clock signal distribution networks face challenges in maintaining the duty-cycle quality of internal clock signals, leading to performance reduction and potential functional issues due to process-induced distortion, particularly when using single-ended clock signals which are more susceptible to distortion compared to differential signals.
Innovation Solution
A duty-cycle correction circuit is introduced that includes a global clock tree circuit, differential-to-single-ended clock drivers with adjustable output drive strength, and adjustable delay models to synchronize and compensate for phase differences, ensuring duty-cycle correction by generating and distributing clock signals with a 50% duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If differential clock paths are used to distribute internal clock signals, then duty-cycle distortion is reduced, but power consumption increases significantly and space requirements increase
Solution Approach 1:
The patent creates a simplified single-ended clock path that copies the essential function of differential clock paths for duty-cycle correction, eliminating the need for complex differential signaling while maintaining duty-cycle quality through a single clock path with correction circuitry
Solution Approach 2:
The patent changes the signaling parameter from differential to single-ended and introduces adjustable delay parameters in the clock path to compensate for process-induced distortion, achieving duty-cycle correction without the power and space costs of differential paths
2Manufacturing precision
If differential clock paths are used to distribute internal clock signals, then duty-cycle distortion is reduced, but the space required for parallel clock paths increases
Solution Approach 1:
The patent uses a single-ended clock path that copies the duty-cycle correction function of differential paths, requiring only one clock path instead of parallel differential paths, thereby reducing the area occupied by clock distribution circuitry
Solution Approach 2:
The patent merges the clock distribution function into a single path rather than using separate parallel paths for differential signaling, consolidating the clock network and reducing the total area required for clock distribution
3Use of energy by moving object
If single-ended clock signals are used for distribution, then power consumption and space requirements are reduced, but susceptibility to process-induced duty-cycle distortion increases
Solution Approach 1:
The patent introduces a feedback mechanism where the single-ended clock signal is delayed and fed back to adjust the clock path timing, enabling automatic compensation for process-induced duty-cycle distortion and improving reliability while maintaining low power consumption
Solution Approach 2:
The patent makes the clock path dynamic by introducing adjustable delay elements that can be tuned to compensate for process variations, allowing the single-ended path to adapt to different process conditions and maintain duty-cycle accuracy
Data Source
AI summary
Duty-cycle correction circuits, clock distribution networks, and methods for correcting duty-cycle distortion are disclosed, including methods and apparatus for correcting duty-cycle distortion of differential output clock signals provided from a clock distribution network. In one such method, a single-ended clock signal is generated from differential input clock signals for distribution over a clock distribution network and from which the differential output clock signals are generated. A delay of a model delay path is matched to a propagation delay of the clock distribution network, and the single ended clock signal is adjusted to compensate for duty-cycle distortion.