Serial Interface Phase Calibration for Reliable Data Sampling
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Solution Overview
Problem
High-speed serial interfaces face issues with unreliable data transfer due to uncalibrated clock signals, leading to error-prone data reception.
Innovation Solution
A phase calibration method that involves receiving serial clock and data signals, sweeping phase codes to identify specific threshold points, determining an average phase code, and applying it to a phase interpolator to align the clock signal with the data eye, ensuring accurate data sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional phase calibration methods are used, then clock signal phase can be adjusted, but the calibration process is time-consuming and complex
Solution Approach 1:
The patent applies preliminary action by performing a coarse phase calibration first to bring the clock signal close to the optimal phase, then performing a fine calibration to achieve precise alignment. This two-stage approach prepares the system in advance for the final precise calibration, reducing the total calibration time while maintaining accuracy.
Solution Approach 2:
The calibration process is segmented into multiple independent stages: coarse calibration using a wide phase range, fine calibration using a narrow phase range around the coarse result, and verification stages. Each segment focuses on a specific aspect of phase alignment, making the overall complex process more manageable and faster to execute.
2Measurement precision
If extensive phase code sweeping is performed to achieve precise calibration, then phase alignment accuracy improves, but the calibration complexity increases
Solution Approach 1:
The phase code sweeping is segmented into a coarse sweep covering a wide phase range (e.g., 0-360 degrees) and a fine sweep covering a narrow range around the coarse result (e.g., ±10 degrees). This segmentation allows the system to achieve high precision without performing an exhaustive sweep of the entire phase range, thereby reducing calibration complexity while maintaining accuracy.
Solution Approach 2:
The coarse phase calibration serves as a preliminary action that identifies the approximate optimal phase region. This preliminary result is then used to guide the fine calibration sweep, constraining it to a smaller phase range. This approach achieves high measurement precision without requiring a complex exhaustive search of all possible phase codes.
3Measurement precision
If multiple calibration points are sampled to improve accuracy, then phase calibration accuracy increases, but the number of operations and time required increases
Solution Approach 1:
The calibration sampling is segmented into coarse sampling at multiple phase points during the initial wide-range sweep, and fine sampling at fewer but more densely spaced points during the subsequent narrow-range sweep. This segmentation allows the system to gather sufficient data for high accuracy while minimizing the total number of sampling operations through the two-stage approach.
Solution Approach 2:
The coarse calibration with its broader phase sampling serves as a preliminary action that identifies the general optimal phase region. This preliminary information allows the fine calibration to focus sampling efforts on a smaller, more critical phase range, thereby achieving high calibration accuracy with fewer total sampling operations and improved calibration speed.
Data Source
AI summary
A phase calibration method includes sweeping phase codes applicable to a serial clock signal, identifying a first, a second, a third, and a fourth phase code, wherein the first phase code causes zero plus a first threshold number of bits extracted from the serial data signal to be a particular value, wherein the second phase code causes all minus a second threshold number of bits extracted from the serial data signal to be the particular value, wherein the third phase code causes all minus a third threshold number of bits extracted from the serial data signal to be the particular value, wherein the fourth phase code causes zero plus a fourth threshold number of bits extracted from the serial data signal to be the particular value, determining an average phase code based on the identified phase codes.