Reference Clock Duty Cycle Adjustment for Skewed Data Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Data recovery in integrated circuits is compromised due to skew between the reference clock and data signals, leading to errors in sampling, especially when the phase relationship between the clock and data signals is non-stationary, causing complexity in clock and data recovery operations.
Innovation Solution
A receive interface circuit with a duty cycle adjustment circuit that adjusts the duty cycle of the reference clock signal based on selected ranges and units of duty cycle adjustment, generating an adjusted reference clock signal to align with the data signal, thereby improving data recovery integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the duty cycle of the reference clock signal is fixed, then the circuit operation is simple, but data recovery errors occur due to skew between clock and data signals
Solution Approach 1:
The patent implements dynamic duty cycle adjustment by making the duty cycle of the reference clock signal variable rather than fixed. The duty cycle adjustment circuit continuously or adaptively modifies the duty cycle based on detected skew conditions, allowing the system to maintain optimal data sampling timing despite variations in skew. This dynamic adaptation resolves the contradiction by enabling reliable data recovery through active compensation while managing complexity through targeted adjustment mechanisms.
Solution Approach 2:
The patent changes the duty cycle parameter of the reference clock signal to compensate for skew between clock and data signals. By adjusting this specific parameter (duty cycle) within a controlled range, the system can align the sampling point with the optimal data transition window. This parameter change approach allows the system to maintain reliability through adaptive tuning while keeping the overall circuit architecture relatively simple.
2Adaptability or versatility
If the phase relationship between clock and data signals is non-stationary, then the system can adapt to varying conditions, but the complexity of clock and data recovery operations increases
Solution Approach 1:
The patent performs preliminary duty cycle adjustment before data sampling occurs. The system proactively modifies the reference clock duty cycle based on anticipated or detected skew conditions, preparing the sampling timing in advance. This preliminary action allows the system to handle non-stationary phase relationships by pre-positioning the sampling point, reducing the complexity of real-time recovery operations while maintaining adaptability to varying phase conditions.
Solution Approach 2:
The patent implements feedback mechanisms that monitor the phase relationship between clock and data signals and use this information to adjust the duty cycle accordingly. The feedback loop detects skew conditions and automatically modifies the reference clock duty cycle to maintain optimal sampling timing. This feedback-driven approach enables the system to adapt to non-stationary phase relationships while managing complexity through automated closed-loop control rather than complex open-loop recovery operations.
Data Source
AI summary
A receive interface circuit includes a duty cycle adjustment circuit that adjusts the duty cycle of a reference clock signal based, at least in part, on a selected number of duty cycle adjustment units and a selected range of duty cycle adjustment. The duty cycle adjustment circuit may select as the reference clock signal one of a clock signal and at least a lower version of the clock signal in parallel with the duty cycle adjustment.