Dual-Crystal Oscillator Layout for Thermal Frequency Stability
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Solution Overview
Problem
Existing oscillation apparatuses using two crystal units suffer from reduced frequency stability over time due to temperature differences between the units, caused by heat generated by the integrated circuit chip, which breaks down the correspondence relationship with correction data, leading to errors in frequency correction.
Innovation Solution
An oscillation apparatus with a first crystal unit, a second crystal unit, and an integrated circuit chip, where the crystal units are arranged bilaterally symmetrical with respect to the gravity center of the IC chip, and the distances from the IC chip to the crystal units' excitation electrodes are within a predetermined range (0.95 to 1.05) to ensure equal heat transfer, reducing temperature differences and improving frequency stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the integrated circuit chip is placed close to the crystal units for compact design, then the device size is reduced, but the heat generated by the IC chip causes temperature differences between the two crystal units, leading to frequency instability
Solution Approach 1:
The patent applies asymmetry by intentionally creating a temperature difference between the reference crystal unit and the measurement crystal unit through asymmetric thermal design. The reference crystal unit is positioned closer to the IC chip or in a region with better heat dissipation, while the measurement crystal unit is positioned farther away or in a region with poorer heat dissipation. This controlled asymmetric thermal environment allows the measurement crystal to experience temperature variations that need to be compensated, while the reference crystal maintains a more stable temperature closer to the IC chip's operating temperature.
Solution Approach 2:
The patent applies local quality by creating different thermal characteristics in different regions of the device. The reference crystal unit is designed to operate in a thermally stable region close to the IC chip, while the measurement crystal unit operates in a region that experiences temperature variations. This local differentiation of thermal properties allows the system to measure temperature effects on crystal frequency while maintaining a stable reference.
2Ease of manufacture
If the crystal units are positioned at different distances from the IC chip, then the device layout is simplified, but the temperature difference between the crystal units causes errors in frequency correction
Solution Approach 1:
The patent applies asymmetry by intentionally creating a temperature difference between the reference crystal unit and the measurement crystal unit through asymmetric thermal design. The reference crystal unit is positioned closer to the IC chip or in a region with better heat dissipation, while the measurement crystal unit is positioned farther away or in a region with poorer heat dissipation. This controlled asymmetric thermal environment allows the measurement crystal to experience temperature variations that need to be compensated, while the reference crystal maintains a more stable temperature closer to the IC chip's operating temperature.
3Power
If the IC chip generates heat during operation, then the oscillation circuits function properly, but the heat causes temperature differences between the two crystal units, breaking down the correspondence relationship with correction data
Solution Approach 1:
The patent applies local quality by creating different thermal characteristics in different regions of the device. The reference crystal unit is designed to operate in a thermally stable region close to the IC chip, while the measurement crystal unit operates in a region that experiences temperature variations. This local differentiation of thermal properties allows the system to measure temperature effects on crystal frequency while maintaining a stable reference.
Solution Approach 2:
The patent applies feedback by using the measurement crystal unit to detect temperature variations caused by IC chip operation. The frequency difference between the reference and measurement crystal units provides feedback information about the thermal environment, which is then used to correct the frequency output and maintain accuracy despite temperature changes.
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 configuration stabilizes the oscillation frequency by accurately correcting the output frequency setting based on environmental temperature, enhancing the accuracy of temperature detection and reducing errors caused by temperature deviations, thus maintaining high frequency stability.
Implementation Method 1
the integrated circuit chip generates heat by the operation of the crystal oscillator
Implementation Method 2
A crystal unit used for a crystal oscillator has a frequency versus temperature characteristic where an oscillation frequency changes corresponding to the temperature
Data Source
AI summary
An oscillation apparatus corrects a setting value for an output frequency based on a detection result of an environmental temperature. The oscillation apparatus includes a first crystal unit, a second crystal unit, an integrated circuit chip, and a container. The first crystal unit includes first excitation electrodes on respective surfaces of a crystal element. The second crystal unit includes second excitation electrodes on respective surfaces of a crystal element. The integrated circuit chip includes a first oscillation circuit, a second oscillation circuit, and a correction unit. The container houses the first crystal unit, the second crystal unit, and the integrated circuit chip. Assuming that distances from a gravity center position of the integrated circuit chip to respective gravity center positions of the first excitation electrodes and the second excitation electrodes in plan view are denoted by D1 and D2, D1/D2 is within a predetermined range close to 1.