Temperature Data Smoothing Circuit for Digital Oscillator Stability
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Solution Overview
Problem
Existing A/D conversion techniques in digital type oscillators, such as DTCXO, face issues with frequency drift due to rapid changes in temperature detection data, leading to communication errors and frequency hopping, which are not effectively addressed by current methods.
Innovation Solution
A circuit device with a D/A converter, comparison portion, and processing portion that compares temperature detection voltage with D/A conversion voltage, determining temperature detection data to ensure a change of k×LSB or less between output timings, thereby minimizing defects caused by temperature data changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional A/D conversion is performed without considering temperature change rate, then A/D conversion can be performed continuously, but rapid changes in temperature detection data cause frequency drift and communication errors
Solution Approach 1:
The patent applies preliminary action by predicting the next temperature detection data value based on the previous value and expected temperature change rate before actual A/D conversion occurs. This prediction allows the system to prepare appropriate digital output values in advance, preventing rapid changes that would cause frequency drift while maintaining efficient conversion operations.
Solution Approach 2:
The patent implements feedback by continuously monitoring the relationship between consecutive temperature detection data values and adjusting the A/D conversion output accordingly. When the difference between consecutive values exceeds a predetermined threshold, the system modifies the conversion behavior to suppress rapid changes, ensuring frequency stability while maintaining conversion efficiency.
2Measurement precision
If A/D conversion output changes rapidly to reflect real temperature changes, then temperature detection accuracy is improved, but frequency drift and communication errors occur
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the output value of A/D conversion based on the detected temperature change rate. When temperature changes are within normal ranges, the system outputs accurate conversion results. When rapid changes are detected, the system modifies the output parameter to suppress excessive variations, thereby maintaining communication reliability while preserving essential temperature information.
3Productivity
If conventional successive comparison A/D conversion is used, then conversion can be performed continuously, but inefficient conversion occurs when great changes in temperature detection data are permitted
Solution Approach 1:
The patent applies preliminary action by calculating predicted temperature detection data values before actual conversion based on previous values and expected change rates. This preliminary calculation allows the system to determine appropriate output values in advance, enabling efficient conversion operations that maintain frequency stability without requiring continuous full-resolution conversions.
Data Source
AI summary
A circuit device includes a D/A converter, a comparator that compares a temperature detection voltage from a temperature sensor unit with a D/A conversion voltage from the D/A converter, and a processing circuit that executes a determination process based on a comparison result from the comparator, and obtains temperature detection data as a result of A/D conversion of the temperature detection voltage, in which, the processing circuit determines the temperature detection data so that a change in the temperature detection data at a second output timing following a first output timing with respect to the temperature detection data at the first output timing is equal to or less than k×LSB.