Clock Skew Control Using Multi-Sensor Delay Adjustment
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Solution Overview
Problem
Existing clock skew adjustment systems in integrated circuits face issues with jitter due to uncertainty regions in skew sensors, leading to unstable clock signal adjustments.
Innovation Solution
The system employs multiple skew sensors and delay units to generate and adjust clock signals, allowing for precise control of delay settings to minimize jitter and achieve long-term stability by dynamically controlling the window of uncertainty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple skew sensor with a single delay unit is used for clock skew adjustment, then the device complexity is low, but jitter occurs due to uncertainty regions causing the system to jump between delay settings
Solution Approach 1:
The patent divides a single skew sensor into multiple skew sensors (first skew sensor and second skew sensor), each with different delay units. This segmentation allows the system to cover a wider detection range and avoid the uncertainty region that causes jitter, while each individual sensor remains relatively simple in structure.
Solution Approach 2:
The patent extends the detection capability by adding another dimension of delay adjustment through the second skew sensor with different delay units. This multi-dimensional approach allows the system to resolve clock skew more precisely by comparing results from multiple sensors with different delay characteristics, preventing the oscillation between delay settings.
2Device complexity
If delay units with larger step sizes are used to simplify the delay control, then the device complexity is reduced, but the measurement precision of clock skew decreases leading to jitter
Solution Approach 1:
The patent segments the delay control into multiple delay units with different step sizes across different skew sensors. The first skew sensor has delay units with a first step size, while the second skew sensor has delay units with a second step size. This segmentation allows the system to achieve fine-grained clock skew adjustment by combining results from sensors with different resolution levels, maintaining measurement precision without requiring all sensors to have complex fine-step delay units.
Solution Approach 2:
Different skew sensors are assigned different delay unit characteristics (different step sizes) according to their specific detection needs. This local quality approach allows each sensor to operate optimally in its specific range, with the system as a whole achieving both simplicity and precision through the combination of heterogeneous delay units.
3Ease of manufacture
If a single skew sensor is used to minimize device complexity, then the manufacturing cost is reduced, but the reliability of clock skew adjustment deteriorates due to jitter from uncertainty regions
Solution Approach 1:
The patent implements a segmented skew sensing approach using multiple skew sensors with different delay units instead of a single complex sensor. Each sensor can be manufactured using similar processes, but their combination provides enhanced reliability by eliminating the uncertainty region problem that causes jitter in single-sensor systems.
Solution Approach 2:
The patent merges the outputs of multiple skew sensors with different delay characteristics to achieve reliable clock skew adjustment. By combining the detection results from the first skew sensor and second skew sensor, the system eliminates the uncertainty region effects that plague single-sensor systems, achieving high reliability without requiring any single sensor to be overly complex.
Data Source
AI summary
An apparatus of performing a clock skew adjustment between at least first and second clock signals includes first and second skew sensors and a skew controller. The first skew sensor receives a third clock signal obtained by delaying the first clock signal by a first delay and a fourth clock signal obtained by delaying the second clock signal by a second delay, and generates first information based on the third and fourth clock signals. The second skew sensor receives a fifth clock signal obtained by delaying the first clock signal by a third delay and a sixth clock signal obtained by delaying the second clock signal by a fourth delay, and generates second information based on the fifth and sixth clock signals. Each of the first and second information varies depending on the clock skew. The skew controller performs the clock skew adjustment based on the first and second information.