Adaptive Filter Circuit for Fast PLL Locking and Low Jitter
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Solution Overview
Problem
Conventional digital phase locked loops (PLLs) face reduced operating speed and increased locking time due to excessive filtering, which can lead to serious jitter and instability in output signals.
Innovation Solution
A filter circuit comprising a filtering unit and a weight generation unit that monitors signal variations to generate weight information, allowing for adaptive adjustment of signal processing to optimize circuit operation, thereby enhancing operating speed without compromising stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter is applied to ensure stable operation of a circuit, then stability is improved, but operating speed is reduced
Solution Approach 1:
The patent applies dynamics by making the filter weight adjustable and adaptive rather than fixed. The weight generation unit dynamically adjusts the filter weight based on monitored signal variations, allowing the filter to adapt its strength according to operating conditions. This resolves the contradiction by enabling the system to have strong filtering when needed for stability and weak filtering when speed is prioritized.
Solution Approach 2:
The patent changes the parameter of filter weight from a fixed value to a dynamically adjustable parameter. By monitoring signal variations and adjusting the weight accordingly, the system can optimize the balance between stability and operating speed. The weight generation unit modifies the filter parameter based on real-time signal conditions, allowing the circuit to maintain stability when variations are high while operating at higher speeds when variations are low.
2Reliability
If excessive filtering is applied to reduce jitter, then noise removal is improved, but locking time is increased
Solution Approach 1:
The patent makes the filtering strength dynamic through the weight generation unit that adjusts the filter weight based on monitored signal variations. During initial locking, the filter applies minimal weighting to allow rapid frequency acquisition. Once locked, the filter increases weighting to reduce jitter and noise effectively. This dynamic adjustment resolves the contradiction between noise removal and locking time.
Solution Approach 2:
The patent implements periodic monitoring of signal variations and periodic adjustment of filter weight. The weight generation unit continuously monitors the filtered signal and adjusts the weight in periodic cycles, allowing the system to optimize filtering strength at different stages of operation. This periodic action enables rapid locking initially followed by enhanced noise removal once stability is achieved.
Data Source
AI summary
A filter circuit includes a filtering unit configured to filter an input signal and generate an output signal, and a weight generation unit configured to monitor a variation of the output signal and generate weight information based on the monitored variation.