Physical Quantity Sensor Calibration for A/D and D/A Variation Correction
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Solution Overview
Problem
Existing physical quantity sensor devices face challenges in accurately correcting characteristic variations of both the sensor and peripheral circuits, leading to manufacturing management issues and quality characteristic problems due to the inability to individually grasp variations in A/D and D/A converters, which also limits overall accuracy and increases costs.
Innovation Solution
A physical quantity sensor device with a first and second conversion section, computing section, and analog input/output section, where initial output characteristics are adjusted before conversion, allowing for high-accuracy correction of output signals, enabling accurate digital computation and analog output with reflected adjustment information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of A/D and D/A converters is increased to improve correction accuracy, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by measuring and storing the initial output characteristics of the A/D and D/A converters during the manufacturing process. These characteristics are used to calculate correction values that are stored in memory. During operation, the correction values are applied to compensate for converter variations, achieving high correction accuracy without requiring increased converter resolution.
2Measurement precision
If the computation complexity is increased to improve correction accuracy, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent performs the complex computation work in advance during manufacturing. The initial output characteristics are measured and used to calculate correction values through polynomial fitting. These pre-calculated correction values are stored in memory and simply applied during operation, avoiding the need for complex real-time computation while achieving high correction accuracy.
Solution Approach 2:
The patent replaces complex real-time computational mechanisms with a simpler memory-based lookup and application system. Instead of performing complex computations during operation, the system uses pre-calculated correction values stored in memory, substituting the computational mechanism with a storage and retrieval mechanism.
3Manufacturing precision
If individual correction of A/D and D/A converters is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by separately measuring and correcting the A/D converter and D/A converter independently. The initial output characteristics of each converter are measured separately, and separate correction values are calculated and stored for each. This segmented approach allows precise correction of each converter's specific variations without requiring complex inter-converter coordination.
Solution Approach 2:
The patent introduces correction values as an intermediary element that mediates between the imperfect A/D and D/A converters and the desired accurate output. These correction values, stored in memory, act as a bridge that compensates for converter variations, allowing simple converter hardware to achieve precise correction through the intermediary correction data.
4Measurement precision
If high-resolution converters are used to improve correction accuracy, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent changes the approach from improving hardware parameters (converter resolution) to optimizing software parameters (correction values). Instead of using high-resolution converters that are more expensive to manufacture, the patent uses standard-resolution converters with pre-calculated correction values applied during operation, achieving the same effective precision at lower manufacturing cost.
Data Source
AI summary
An analog signal is supplied to a first conversion section of a physical quantity sensor device, converted to digital, and set to be an initial output value of the first conversion section. Adjustment information for the first conversion section is calculated based on the error between the initial output value and a target output value of the first conversion section. Before an initial output value of a physical quantity sensor is measured for calculating initial setting information of a physical quantity sensor device, the first conversion section is adjusted based on the adjustment information. Also, a digital signal is supplied to a second conversion section of the physical quantity sensor device, converted to analog, and set to be an initial output value of the second conversion section. The second conversion section is adjusted based on adjustment information for the second conversion section.