Oscillator Temperature Control With Higher-Order Error Cancellation
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Solution Overview
Problem
Conventional temperature control circuits for quartz crystal oscillators fail to accurately suppress frequency temperature fluctuations due to residual nonlinear error components, leading to degraded frequency temperature fluctuation characteristics.
Innovation Solution
A temperature control circuit with a target temperature generation circuit, a temperature sensor, a driving amount detection circuit, a drive circuit, and a cancellation circuit that corrects the target temperature in higher orders to cancel out second or higher order fluctuation components, ensuring accurate temperature control and reduced frequency fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional first-order correction is applied to suppress frequency temperature fluctuations, then linear temperature variations are compensated, but residual nonlinear error components remain causing degraded frequency stability
Solution Approach 1:
The patent changes the parameter of target temperature from a fixed constant to a dynamically adjusted value that incorporates higher-order correction terms. The target temperature generation circuit computes Tgt' = Tgt + a1·Ta + a2·Ta² + ... + an·Taⁿ, where Ta is ambient temperature and ai are correction coefficients. This parameter transformation enables compensation of nonlinear temperature fluctuations that first-order correction cannot address, thereby improving frequency stability without sacrificing temperature control accuracy.
Solution Approach 2:
The patent implements a feedback mechanism where the ambient temperature detection value is fed back through the target temperature generation circuit to continuously adjust the target temperature based on current environmental conditions. This closed-loop feedback ensures that the temperature control system adapts to varying ambient temperatures and compensates for both linear and nonlinear effects, resolving the contradiction between frequency stability and temperature control accuracy.
2Reliability
If higher-order correction terms are added to target temperature, then nonlinear temperature fluctuations are suppressed, but device complexity increases
Solution Approach 1:
The target temperature generation circuit is designed to perform multiple functions: it generates the base target temperature, detects ambient temperature, computes higher-order correction terms, and outputs the corrected target temperature. By making this single circuit multi-functional, the patent avoids the need for separate correction circuits for each order, thereby suppressing nonlinear temperature fluctuations while minimizing the increase in device complexity.
Solution Approach 2:
The patent merges the ambient temperature detection function and the higher-order correction computation function into the existing target temperature generation circuit. This consolidation eliminates the need for separate correction circuits and reduces overall system complexity while achieving effective suppression of nonlinear temperature fluctuations through the combined functionality.
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 enables more precise temperature control, effectively suppressing frequency temperature fluctuations and improving oscillation control accuracy by correcting for nonlinear components, thereby maintaining the oscillation frequency at an intended value.
Implementation Method 1
a temperature sensor arranged in the package and configured to detect temperature in the package
Implementation Method 2
a heat generation circuit stored in a package... drive circuit configured to control the driving amount so that the detection temperature detected by the temperature sensor coincides with the target temperature
Data Source
AI summary
In-package temperature is controlled with higher accuracy. To this end, a temperature control circuit includes a temperature sensor arranged in a package and detecting temperature in the package, a heater current detection circuit detecting a driving amount of a heater, a target temperature generation circuit generating a target temperature from an intended temperature of a resonator and a detection value of the driving amount detected by the heater current detection circuit, a heater current driver controlling the heater so that the detection temperature detected by the temperature sensor coincides with the target temperature, and an Nth-order correction circuit receiving the detection value of the driving amount detected by the heater current detection circuit or a signal based on the target temperature and cancelling influence of a second or higher order fluctuation component generated in the heater current detection circuit on temperature of the resonator.