Dual Quartz Oscillator Temperature Compensation for Stable Frequency
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Solution Overview
Problem
Existing oscillation devices face challenges in achieving high-frequency stability and accuracy due to limitations in temperature compensation, particularly with TCXO, which require large memory for data storage and suffer from inaccurate temperature detection, leading to inferior frequency accuracy.
Innovation Solution
The oscillation device employs two quartz-crystal oscillators on a common quartz-crystal piece, with a frequency difference detecting unit calculating a compensation value based on the difference between their frequencies at reference and ambient temperatures, allowing for high-accuracy temperature compensation without the need for complex manufacturing processes or large memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a TCXO with a voltage variable capacitance element is used for temperature compensation, then the device complexity and power consumption are reduced, but the frequency stability with respect to temperature becomes inferior compared to OCXO
Solution Approach 1:
The patent merges two quartz-crystal oscillators into a single device structure, where one oscillator serves as the reference and the other as the measurement oscillator. This integration allows temperature compensation while maintaining compact device complexity and avoiding the need for separate temperature sensors and large memory systems.
Solution Approach 2:
The patent implements a feedback mechanism where the frequency difference between two oscillators is continuously measured and used to generate a compensation signal. This feedback loop enables automatic temperature compensation, improving frequency stability without requiring complex external control systems.
2Measurement precision
If the temperature compensation control is conducted finely using a large-capacity memory to store frequency-temperature characteristic data, then the frequency accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent enables the oscillation device to perform its own temperature measurement and compensation using its internal oscillators, eliminating the need for external temperature sensors and large memory systems. The device uses its inherent frequency-temperature characteristics to generate compensation signals autonomously.
Solution Approach 2:
The patent changes the approach from storing extensive temperature-compensation data in memory to using a simple frequency difference measurement. By measuring the frequency difference between two oscillators and using this difference as a temperature indicator, the system achieves accurate compensation with minimal data storage requirements.
3Device complexity
If a thermistor is used as the temperature detector, then the device complexity is reduced, but the detection accuracy is limited and cannot be improved even when the amount of data is enlarged
Solution Approach 1:
The patent creates a copy of the temperature sensing function using a second quartz-crystal oscillator that operates at a different frequency. This oscillator serves as a reference to measure temperature-induced frequency changes, providing high-accuracy temperature detection without using traditional temperature sensors like thermistors.
4Device complexity
If the temperature detector and the quartz-crystal oscillator are disposed at different positions, then the device structure is simplified, but the actual temperature information of the quartz-crystal oscillator cannot be correctly obtained
Solution Approach 1:
The patent merges the temperature measurement function directly into the oscillator structure by using a second quartz-crystal oscillator as the temperature sensor. Since both oscillators are housed in the same case and subjected to the same temperature conditions, the frequency difference accurately reflects the temperature experienced by the main oscillator without requiring separate positioning.
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 enables high-accuracy temperature compensation of output frequencies, reducing device complexity and memory requirements while improving frequency stability and accuracy, and eliminating the need for precise temperature detection.
Implementation Method 1
a first quartz-crystal oscillator structured by providing first electrodes on a quartz-crystal piece; a second quartz-crystal oscillator structured by providing second electrodes on the quartz-crystal piece shared with the first quartz-crystal oscillator
Data Source
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AI summary
To perform, in an oscillation device compensating an output frequency based on a detection result of ambient temperature, temperature compensation of the output frequency with high accuracy. First and second quartz-crystal oscillators are structured by using a common quartz-crystal piece, and when oscillation outputs of first and second oscillation circuits respectively connected to these quartz-crystal oscillators are set to f1, f2, and oscillation frequencies of the first and the second oscillation circuits at a reference temperature are set to f1r, f2r, respectively, a frequency difference being a difference between a value corresponding to a difference between f1 and f1r and a value corresponding to a difference between f2 and f2r is treated as a temperature at that time. Further, based on the frequency difference, a frequency compensation value is determined through polynomial approximation.