PLL Operating Curve Selection for Wide-Range Frequency Locking
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Solution Overview
Problem
Conventional phase lock loops (PLLs) face challenges in efficiently selecting the appropriate operating curve for generating oscillation signals across a wide range of frequencies, leading to reduced flexibility and precision in high-frequency applications.
Innovation Solution
A PLL system with a controller that operates in an initial mode to recursively determine a selection signal by comparing feedback and divided signals, switching to a normal mode once the selection signal converges, allowing the voltage-controlled oscillator (VCO) to select an appropriate operating curve based on these signals, thereby enabling precise frequency generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multi-operating curves are used to expand frequency range, then frequency coverage is improved, but operating curve selection complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal operating curve selections in a lookup table during the design phase. The controller recursively determines the selection signal by calculating differences between feedback and divided signals, then uses this information to quickly select the appropriate operating curve without real-time complex calculations, thus resolving the contradiction between wide frequency coverage and selection complexity
Solution Approach 2:
The patent introduces an intermediary mechanism - the selection signal and lookup table - that mediates between the desired frequency output and the appropriate operating curve. This intermediary layer simplifies the selection process by translating frequency requirements into predefined curve selections, reducing the complexity of operating curve selection while maintaining wide frequency coverage
2Measurement precision
If conventional operating curve selection is used, then device simplicity is maintained, but frequency generation precision deteriorates
Solution Approach 1:
The patent applies feedback by continuously comparing the feedback signal with the divided signal and using the calculated difference to recursively determine the selection signal. This feedback mechanism enables precise frequency generation by dynamically adjusting the operating curve selection based on actual performance, resolving the contradiction between precision and controller complexity
Solution Approach 2:
The patent introduces dynamics by making the operating curve selection adaptive rather than fixed. The controller dynamically adjusts the selection signal based on real-time signal comparisons and convergence criteria, enabling precise frequency generation across different operating conditions while managing controller complexity through systematic algorithms
3Speed
If recursive determination with signal comparison is implemented, then convergence speed is improved, but initial mode complexity increases
Solution Approach 1:
The patent applies preliminary action by implementing the recursive determination and signal comparison mechanisms during the initial mode to quickly establish the correct operating curve before switching to normal operation. This preliminary convergence process, while complex, is performed only once during initialization, thus achieving fast convergence without permanently increasing overall system complexity
Solution Approach 2:
The patent segments the PLL operation into distinct modes (initial mode and normal mode), isolating the complex recursive determination process to the initial mode. This segmentation allows fast convergence during initialization while keeping the normal operating mode simple and efficient, resolving the contradiction between convergence speed and overall system complexity
Data Source
AI summary
A PLL is provided, comprising a first divider, a PFD, a loop filter, a VCO, a second divider and a controller. The first divider receives a reference signal and divides the reference signal by R to obtain a divided signal. The PFD compares the divided signal and a feedback signal to generate a compared The VCO selects one of a plurality of operating curves for oscillation based on a selection signal, and generates an oscillation signal based on an operating voltage generated by signal the loop filter. The second divider divides the oscillation signal by N to obtain the feedback signal. The controller operates in an initial mode to recursively determine the selection signal by calculating differences of the feedback signal and the divided signal. When the selection signal converges to stable, the PLL switches to a normal mode to operate on the corresponding operating curve.