Crystal Oscillator Heater Control Using Frequency-Difference Sensing
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Solution Overview
Problem
Existing crystal oscillators face challenges in maintaining temperature stability due to variations in oscillation frequency change ratios with temperature, limiting their application in high-stability clock signal requirements, especially in base stations and relay stations, where the oven-controlled crystal oscillator (OCXO) is not cost-effective and the temperature-compensated crystal oscillator (TCXO) faces issues with heater control circuit size and sensitivity variations.
Innovation Solution
A crystal oscillator design that uses a frequency difference detection method to generate a temperature detection value from the difference between oscillation frequencies of two crystal units, with a heating control system that adjusts based on accumulated and rounded digital values, allowing independent selection of rounding factor and accumulation number to stabilize temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the oscillation frequency change ratio is increased to improve temperature detection sensitivity, then temperature detection precision is improved, but the heater control circuit size increases and erroneous operations occur
Solution Approach 1:
The patent applies dynamics by making the accumulation number configurable rather than fixed. The control unit can dynamically adjust the accumulation number based on the detected oscillation frequency change ratio, allowing the system to adapt to different crystal pieces with varying temperature characteristics. This dynamic adjustment prevents the control circuit from needing to handle extreme sensitivity variations through fixed complex circuitry.
Solution Approach 2:
The patent changes the parameter of accumulation number to optimize temperature detection. By adjusting the accumulation number according to the oscillation frequency change ratio, the system can reduce noise and improve measurement precision without requiring complex hardware. The configurable accumulation number acts as a software-based parameter adjustment that simplifies the overall control circuit design.
2Measurement precision
If the oscillation frequency change ratio is increased to improve temperature detection sensitivity, then temperature detection precision is improved, but heater control stability deteriorates due to momentary significant changes
Solution Approach 1:
The patent applies dynamics by making the accumulation number configurable rather than fixed. The control unit can dynamically adjust the accumulation number based on the detected oscillation frequency change ratio, allowing the system to adapt to different crystal pieces with varying temperature characteristics. This dynamic adjustment prevents the control circuit from needing to handle extreme sensitivity variations through fixed complex circuitry.
Solution Approach 2:
The patent implements feedback by using the detected oscillation frequency change ratio to adjust the accumulation number. The control unit continuously monitors the temperature detection results and adjusts the accumulation parameter accordingly, creating a closed-loop system that stabilizes heater control by compensating for momentary significant changes in oscillation frequency.
3Adaptability or versatility
If different crystal pieces with varying cut orientations are used to optimize performance, then oscillation characteristics are improved, but temperature detection sensitivity variations increase
Solution Approach 1:
The patent applies dynamics by making the accumulation number configurable rather than fixed. The control unit can dynamically adjust the accumulation number based on the detected oscillation frequency change ratio, allowing the system to adapt to different crystal pieces with varying temperature characteristics. This dynamic adjustment prevents the control circuit from needing to handle extreme sensitivity variations through fixed complex circuitry.
Solution Approach 2:
The patent changes the parameter of accumulation number to optimize temperature detection. By adjusting the accumulation number according to the oscillation frequency change ratio, the system can reduce noise and improve measurement precision without requiring complex hardware. The configurable accumulation number acts as a software-based parameter adjustment that simplifies the overall control circuit design.
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 reduces temperature detection sensitivity variations, enabling appropriate heater control and improving the freedom of selecting crystal pieces, thus ensuring stable temperature control and preventing erroneous operations in the heater control system.
Implementation Method 1
a heating portion (5) for constantly maintaining an ambient temperature of each of the crystal units (10, 20)
Data Source
AI summary
A crystal oscillator includes: an oscillation circuit; first and second oscillation circuits connected to first and second temperature detection crystal units, respectively; a heating portion configured to constantly maintain an ambient temperature; a frequency difference detection portion that obtains, as a temperature detection value, “{(f2−f1)/f1}−{(f2r−f1r)/f1r}”, where “f1” and “f2” denote oscillation frequencies of the first and second oscillation circuits, respectively, and “f1r” and “f2r” denote oscillation frequencies of the first and second oscillation circuits, respectively, at a reference temperature; an accumulator that accumulates the temperature detection value; a rounding processing portion that performs rounding for the temperature detection value accumulated in the accumulator depending on a rounding factor designated independently from the accumulation number; and a heating control portion that controls power supplied to the heating portion based on the temperature detection value subjected to the rounding in the rounding processing portion.