VCO Frequency Control with Overlapping Hysteresis Thresholds
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Solution Overview
Problem
Conventional non-linear control systems for automatic frequency control of voltage-controlled oscillators in wireless mobile devices face instability and phase jitter due to variability in RF channel quality, leading to processing delays and inefficient resource utilization.
Innovation Solution
The implementation of a hysteresis non-linear frequency tracking system that adjusts adaptive loop filter coefficients based on channel and state metrics, using overlapping thresholds to manage state transitions and minimize phase jitter, thereby stabilizing the frequency tracking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional non-linear control systems are used for automatic frequency control, then frequency tracking is achieved, but instability and phase jitter occur due to frequent switching between control states
Solution Approach 1:
The patent implements dynamic switching between linear and non-linear control modes based on real-time frequency error magnitude. The system transitions from non-linear control (for large frequency offsets) to linear control (for small frequency offsets), optimizing performance across different operating conditions and eliminating the instability caused by fixed control mode switching
Solution Approach 2:
The patent dynamically adjusts control parameters including the switching threshold between control modes and the loop filter coefficients. By adapting these parameters based on channel conditions and frequency error characteristics, the system achieves stable frequency tracking while minimizing phase jitter in varying RF channel environments
2Measurement precision
If filter coefficients are adjusted frequently to track channel changes, then tracking performance improves, but processing delays and resource utilization inefficiency increase
Solution Approach 1:
The patent employs dynamic adaptation of filter coefficients based on the determined state metric and channel conditions. Rather than frequent uniform adjustments, the system adaptively modifies coefficients only when necessary, balancing tracking precision with processing efficiency and resource utilization
Solution Approach 2:
The patent optimizes the adaptation process by dynamically adjusting filter coefficients based on determined state metrics and channel conditions. This selective parameter adjustment achieves optimal tracking performance while minimizing unnecessary processing operations and resource consumption
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the transient response and reduces output phase jitter, ensuring more efficient and stable frequency tracking by dynamically adjusting filter coefficients according to the current operating state and channel conditions.
Implementation Method 1
The implementation of a hysteresis non-linear frequency tracking system that adjusts adaptive loop filter coefficients based on channel and state metrics, using overlapping thresholds to manage state transitions and minimize phase jitter
Data Source
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AI summary
A method and apparatus for non-linear frequency control tracking of a control loop of a voltage controlled oscillator (VCO) in a wireless mobile device receiver is provided. A channel metric based on one or more channel quality indicators associated with a received radio frequency channel is determined and a state metric associated with the current operating state of the control loop are determined. One or more state metric threshold value associated with the determined channel metric, providing hysteresis between operating states, are determined wherein each state metric threshold value is associated with a transition to a possible operating state of the control loop. The control loop transitions from the current operating state to the operating state associated with an exceeded state metric threshold value. Coefficients are provided to an adaptive loop filter of the control loop, wherein the coefficients coefficient are associated with the transitioned operating state.