Phase-Locked Loop Bound Search for Fast Accurate Calibration
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Solution Overview
Problem
Existing phase lock loops in integrated circuits face challenges in achieving fast calibration due to variations in performance caused by process, voltage, and temperature changes, as well as component aging, which can hinder their operation until suitable calibrated values are determined.
Innovation Solution
A method for calibrating phase lock loops involves finding a lower and upper bound for a calibration parameter by stepping through values until the frequency error remains below a threshold, using a controller to determine the calibrated value, which can be applied to both receivers and transmitters, and utilizing a voltage-controlled oscillator with variable capacitors to achieve phase lock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional calibration methods are used, then calibration accuracy is maintained, but calibration time is excessive
Solution Approach 1:
The calibration process is segmented into two distinct phases: a fast coarse calibration phase that quickly establishes initial bounds, and a refined calibration phase that achieves final precision. This segmentation allows the system to trade some initial precision for speed, then recover precision in the second phase, overall reducing total calibration time while maintaining accuracy.
Solution Approach 2:
The patent performs preliminary coarse calibration to establish upper and lower bounds of the calibration parameter before conducting the final precise calibration. This preliminary action of finding bounds first allows the subsequent precise calibration to operate within a narrowed range, significantly reducing the time required to achieve final accuracy.
2Productivity
If fast calibration is implemented, then startup time is reduced, but stability under PVT variations deteriorates
Solution Approach 1:
The patent implements feedback mechanisms where the calibration process continuously monitors frequency error and uses this information to adjust the calibration parameter. The system measures the actual frequency output, compares it to the target frequency, and uses the error signal to guide the calibration parameter adjustment, ensuring stability even under PVT variations.
Solution Approach 2:
The patent dynamically changes calibration parameters based on measured frequency errors and environmental conditions. By adjusting the calibration parameter iteratively and adapting to PVT variations through measured feedback, the system maintains phase lock loop stability while achieving fast startup through efficient parameter optimization.
3Loss of time
If iterative bound-finding method is used, then calibration speed is improved, but computational complexity increases
Solution Approach 1:
The patent employs a dynamic iterative algorithm that adapts its search strategy based on real-time frequency error measurements. The algorithm dynamically adjusts the calibration parameter in successive iterations, changing its approach based on whether the frequency error is positive or negative, thereby optimizing the search path and reducing the number of iterations needed compared to static methods.
Solution Approach 2:
The patent uses a simplified iterative approach that performs partial searches to establish bounds rather than exhaustively searching the entire parameter range. By performing just enough calibration iterations to establish sufficient bounds and achieve acceptable accuracy, the system reduces computational complexity while still improving calibration speed compared to traditional methods.
Data Source
AI summary
Phase lock loop calibration methods can be accelerated, and the accelerated method incorporated in integrated circuits and systems. One illustrative calibration method for use in a controller determines a calibrated value of a calibration parameter for a phase lock loop configured to generate a clock signal. The method includes: finding a lower bound by stepping downward from an initial value of the calibration parameter while a frequency error remains below a predetermined threshold; finding an upper bound by stepping upward from the initial value while the frequency error remains below the predetermined threshold; and using a value greater than or equal to the lower bound and less than or equal to the upper bound as the calibrated value.