Oscillator Circuit Temperature Compensation for Heater-On Frequency Drift
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Solution Overview
Problem
Conventional oscillator circuits experience low frequency stability due to insufficient temperature compensation for crystal resonators and integrated circuits, particularly in regions where the ambient temperature is low and the heater is turned on, leading to variations in oscillation frequency.
Innovation Solution
An oscillator circuit with a first temperature detector, current generator, heaters for the resonator and integrated circuit, and compensation voltage generation circuits to adjust temperatures and compensate for frequency variations, ensuring the internal temperature matches a target temperature and optimizing the resistance value of the second heater to independently control the integrated circuit's temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heater is turned on to maintain temperature in low ambient temperature regions, then the resonator temperature is stabilized, but the integrated circuit temperature varies causing frequency instability
Solution Approach 1:
The patent divides the heating function into two independent heaters: a first heater for the resonator and a second heater for the integrated circuit. This segmentation allows independent temperature control of each component, resolving the contradiction by stabilizing the resonator temperature while separately managing the integrated circuit temperature to prevent frequency instability.
Solution Approach 2:
The patent applies local quality by providing dedicated heating elements positioned near each component (resonator and integrated circuit). The first heater locally heats the resonator while the second heater locally heats the integrated circuit, allowing each component to maintain its optimal temperature independently, thus resolving the frequency stability issue.
2Device complexity
If a single heater is used for both resonator and integrated circuit, then device complexity is reduced, but independent temperature control is lost
Solution Approach 1:
The patent segments the heating system into two independent heaters with separate control pathways. The first heater is dedicated to the resonator while the second heater is dedicated to the integrated circuit. This segmentation enables independent temperature control of each component, achieving the adaptability needed to resolve frequency stability issues while maintaining relatively simple device architecture.
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
The solution achieves high frequency stability by effectively compensating for temperature-induced frequency variations in both the resonator and integrated circuit, even in heater-on regions, thereby enhancing the overall performance of the oscillator circuit.
Implementation Method 1
a first heater, heating the resonator based on the heater current
Implementation Method 2
a second heater, heating the integrated circuit based on the heater current
Data Source
AI summary
An oscillator circuit includes: a first temperature detector, detecting an internal temperature of the oscillator circuit; a current generator, generating a heater current so that the internal temperature matches a target temperature; a first and second heater, heating the resonator and the integrated circuit, respectively, based on the heater current; a second temperature detector, detecting a temperature of the integrated circuit; a first compensation voltage generation circuit, generating a first compensation voltage for compensating for a frequency variation due to a temperature change in the integrated circuit, based on a detection result of the second temperature detector; a second compensation voltage generation circuit, generating a second compensation voltage for compensating for a frequency variation due to a temperature change in the resonator, based on a detection result of the first temperature detector; and an oscillator, generating an oscillation signal based on the first and second compensation voltages.