Quartz Oscillator Temperature Compensation Using Frequency Difference
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Solution Overview
Problem
Existing temperature-compensated quartz-crystal oscillators (TCXOs) face challenges in achieving high frequency accuracy due to limitations in temperature detection accuracy and the inability to accurately obtain actual temperature information of the quartz-crystal resonator, leading to instability and prolonged manufacturing times.
Innovation Solution
An oscillation device utilizing two quartz-crystal resonators with overtone frequencies, where a frequency difference detecting part calculates the difference between the overtone frequencies at current and reference temperatures, enabling accurate temperature compensation of the output frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermistor is used as the temperature detector, then the temperature compensation circuit can be implemented, but the temperature detection accuracy is limited and frequency accuracy cannot be improved
Solution Approach 1:
The patent changes the detection parameter from temperature (measured by thermistor) to frequency difference (measured by frequency difference detecting part). By measuring the frequency difference between two quartz-crystal resonators and using it as a temperature indicator, the system achieves higher measurement precision without being limited by thermistor accuracy
Solution Approach 2:
The patent introduces a frequency difference detecting part as an intermediary between the quartz-crystal resonators and the temperature compensation system. This intermediary converts the physical quantity from temperature to frequency difference, enabling more accurate measurements and better frequency control
2Device complexity
If the temperature detector and quartz-crystal resonator are disposed at different positions, then the circuit structure can be simplified, but actual temperature information of the quartz-crystal resonator cannot be accurately obtained
Solution Approach 1:
The patent uses a second quartz-crystal resonator as a copy or reference of the first resonator. By measuring the frequency difference between the two resonators, the system indirectly obtains temperature information of the first resonator without needing to place a temperature detector directly on it, thus maintaining structural simplicity while achieving accurate temperature measurement
3Manufacturing precision
If a thermostatic oven is used to set temperature compensation amounts, then frequency accuracy can be improved, but manufacturing time is prolonged
Solution Approach 1:
The patent replaces the mechanical/thermal system (thermostatic oven) with an electrical/electronic system (frequency difference detecting part and correction value obtaining part). By using frequency measurements and electronic correction, the system achieves the same frequency accuracy without requiring time-consuming thermal stabilization processes
Solution Approach 2:
The system uses the frequency difference between the two resonators as a self-indicating parameter for temperature. This self-service approach eliminates the need for external thermostatic ovens and complex temperature control equipment during manufacturing, significantly reducing production time while maintaining frequency accuracy
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 allows for highly accurate temperature compensation of the output frequency, reducing manufacturing time and improving frequency stability without the need for complex adjustments or thermostatic ovens.
Implementation Method 1
a first quartz-crystal resonator including a first electrode provided on a quartz-crystal piece; a second quartz-crystal resonator including a second electrode provided on a quartz-crystal piece
Data Source
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AI summary
An oscillation device capable of highly accurate temperature compensation of an output frequency is provided. The oscillation device includes: first and second oscillator circuits oscillating first and second quartz-crystal resonators with overtones respectively; a frequency difference detecting part finding a value corresponding to a difference value between values corresponding to differences between f1 and f1r and between f2 and f2r, where f1 and f2 are oscillation frequencies of the first and second oscillator circuits, and f1r and f2r are oscillation frequencies of the first and second oscillator circuits at a reference temperature; and a correction value obtaining part which, based on the value corresponding to the difference value and a relation between the value corresponding to the difference value and a frequency correction value of the oscillation frequency f1, obtains the frequency correction value of f1, wherein the output frequency is corrected based on the found frequency correction value.