CDR Clock Phase Interpolation for Accurate Data Edge Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In high-speed communication systems, receivers face challenges in recovering clocks from transmitters without accompanying clock signals, leading to potential bit errors due to over/under sampling during data recovery.
Innovation Solution
The implementation of a clock and data recovery (CDR) method using phase-locked loops (PLLs) and a sensing unit with phase interpolators, which generate clock signals to align with data centers and edges, employing thresholds to determine clock conditions and adjust phase differences for accurate sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clock recovery is performed without an accompanying clock signal, then data can be recovered from the incoming data stream, but bit errors occur due to over/under sampling
Solution Approach 1:
The patent implements a feedback mechanism where the receiver continuously monitors the recovered data quality and adjusts the sampling timing accordingly. The phase detector compares the recovered clock phase with the incoming data transitions and generates error signals that feed back to the PLL to correct timing deviations, thereby eliminating bit errors caused by over/under sampling.
Solution Approach 2:
The patent replaces traditional mechanical or simple electronic clock distribution systems with an intelligent CDR system that uses digital signal processing, PLLs, and phase detectors to dynamically generate and adjust clock signals based on the actual data stream characteristics, achieving precise sampling without physical clock signals.
2Ease of operation
If the receiver uses a reference clock of approximately the same frequency, then clock recovery can be initiated, but phase alignment with data transitions must be achieved
Solution Approach 1:
The patent performs preliminary actions by first acquiring a reference clock of approximately the same frequency as the incoming data stream, then uses this preliminary clock to initially sample the data and detect transitions. This preliminary sampling enables the phase detector to begin measuring phase differences and initiating the phase alignment process without waiting for perfect clock conditions.
Solution Approach 2:
The patent implements dynamic phase adjustment where the PLL continuously modifies the reference clock's phase in real-time based on feedback from the phase detector. The system transitions from a static reference clock to a dynamically adjusted clock that automatically tracks and aligns with the incoming data transitions, achieving precise phase alignment adaptively.
Data Source
AI summary
A clock and data recovery (CDR) device is disclosed. The CDR device comprises a sensing unit and an interpolator. The sensing unit is configured to detect a data center, a left data edge and a right data edge of a data on a data stream in a communication system, using a set of thresholds, in response to a first clock signal for sampling the data center, a second clock signal for sampling the left data edge and a third clock signal for sampling the right data edge. Each of the thresholds is related to a different level among data levels of the data. The interpolator is configured to generate the first clock signal based on information on the data center, and generate the second clock signal and the third clock signal based on information on the left and right data edges.