Receiver Clock Calibration for Fractional-Rate Sampling Accuracy
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Solution Overview
Problem
High-speed communication systems, particularly in fractional-rate schemes like quarter-rate schemes, face challenges in accurately sampling data due to phase distortions and path mismatches in clock signals, leading to improper sampling and receiver malfunction.
Innovation Solution
A clock calibration module with a phase control circuit and clock generation module, including phase interpolators, duty cycle correctors, and phase correctors, is introduced to calibrate sampler-input clocks precisely, addressing phase errors and path mismatches by interpolating reference clocks and adjusting phases and duty cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fractional-rate scheme is adopted to accelerate processing speed, then productivity is improved, but phase distortions and path mismatches occur causing sampling accuracy to deteriorate
Solution Approach 1:
The patent applies preliminary action by performing phase calibration of sampler-input clocks before the actual data sampling operation. The clock calibration module pre-adjusts the phases of multiple sampler-input clocks based on path delay characteristics, ensuring that when data sampling occurs, the clocks are already properly aligned. This prevents phase distortion from affecting sampling accuracy while maintaining the high processing speed of fractional-rate schemes.
Solution Approach 2:
The patent implements feedback through a calibration process that measures the actual phase relationships of sampler-input clocks and uses this information to adjust the clock phases. The system monitors sampling results and feeds this information back to the clock calibration module, which then fine-tunes the clock phases to optimize sampling accuracy. This closed-loop feedback mechanism ensures high sampling precision is maintained despite the accelerated processing speed.
2Productivity
If multiple parallel paths are used in fractional-rate scheme, then productivity is improved, but path mismatches cause phase distortion to worsen
Solution Approach 1:
The patent applies local quality by providing individual phase calibration for each parallel path's sampler-input clock. Instead of using a uniform calibration approach for all paths, the system independently adjusts the phase of each clock based on its specific path characteristics and delay. This localized calibration ensures that each path maintains stable phase relationships with the data signal, preventing phase distortion even though multiple parallel paths are used to accelerate processing.
3Measurement precision
If phase calibration is performed for each path separately, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a clock calibration module that can serve multiple parallel paths simultaneously. The calibration logic and control mechanisms are implemented in a unified manner that can handle N different paths through a single multi-functional module, rather than requiring N separate calibration circuits. This approach maintains high phase calibration precision for each individual path while avoiding the linear increase in device complexity that would result from completely separate calibration circuits for each path.
Data Source
AI summary
A clock calibration module, a high-speed receiver, and an associated calibration method are provided. The calibration method is applied to the high-speed receiver having the clock calibration module and a sampler. The sampler samples an equalized data signal with a sampler-input clock. The clock calibration module includes multiple clock generation circuits and a clock calibration circuit. Each of the clock generation circuits includes a phase interpolator, a duty cycle corrector, and a phase corrector. In a calibration mode, the phase interpolator interpolates a reference input clock and generates an interpolated clock accordingly. The duty cycle corrector generates a duty cycle corrected clock based on the interpolated clock. The phase corrector generates the sampler-input clock based on the duty cycle corrected clock. The phase interpolator is controlled by a phase interpolator calibration signal, and the phase corrector is controlled by a phase corrector calibration signal.