Oscillator Aging Correction Using Kalman Filter Parameter Reduction
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Solution Overview
Problem
Existing oscillator technologies, such as OCXO and TCXO, face challenges in maintaining high frequency stability due to aging effects, which require large storage capacity for accurate aging correction, leading to increased circuit size and complexity.
Innovation Solution
A circuit device utilizing a processor that performs a Kalman filter process to update pre-estimated values by adding post-estimated and correction values, allowing for accurate aging correction without the need for extensive storage, thereby reducing processing load and circuit size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a storage with large storage capacity is used to store correspondence relationship information between correction value and elapsed time for aging correction, then aging correction accuracy is improved, but circuit device size increases
Solution Approach 1:
The patent changes the approach from storing complete correspondence relationship information (aging characteristic data) to storing only essential parameters (initial frequency, temperature compensation coefficients, and aging correction coefficients). This parameter reduction enables accurate aging correction while minimizing storage requirements and circuit device size.
Solution Approach 2:
The patent extracts only the necessary parameters from the complete aging characteristic data - specifically the initial frequency, temperature compensation coefficients, and aging correction coefficients. By taking out only these essential elements, the system achieves accurate aging correction without requiring large storage capacity for the entire correspondence relationship information.
2Measurement precision
If extended Kalman filter process is used for aging correction, then correction accuracy is improved, but processing load and circuit size increase
Solution Approach 1:
The patent extracts and implements only the essential components of the Kalman filter algorithm needed for aging correction - specifically the prediction step using stored coefficients and the correction step using current temperature and frequency measurements. By taking out only these necessary computational elements rather than implementing the full extended Kalman filter, the system achieves accurate correction with reduced processing load and smaller circuit size.
Solution Approach 2:
The patent performs preliminary calculation and storage of temperature compensation coefficients and aging correction coefficients during the calibration phase. This preliminary action enables the runtime system to execute simple lookup and calculation operations rather than complex real-time filtering, significantly reducing processing load while maintaining correction accuracy.
Data Source
AI summary
A circuit device includes an oscillation signal generation circuit that generates an oscillation signal having an oscillation frequency set by the frequency control data by using a resonator, and a processor that is configured to perform a signal process on input frequency control data to output frequency control data. The processor is configured to obtain a pre-estimated value x^−(k) at a time step k by adding a post-estimated value x^(k−1) and a correction value D(k−1) at a time step k−1 together during a process of updating a pre-estimated value in a Kalman filter process, and perform aging correction on the frequency control data on the basis of a result of the Kalman filter process.