Two-Stage ADC Reference Compensation for X-Ray Gain Error
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Solution Overview
Problem
Two-stage analog-to-digital converters in digital X-ray imaging systems often experience gain errors due to mismatches between reference voltage sources of the first and second stages, which are exacerbated by temperature changes.
Innovation Solution
Incorporating a current source with a negative temperature coefficient, connected to both reference voltage sources, which includes a voltage generating circuit and a voltage buffer circuit to adjust the output voltage and mitigate temperature-induced voltage offsets, thereby reducing gain errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-stage analog-to-digital converter is used for high-speed and high-precision conversion, then conversion speed and precision are improved, but gain error occurs due to mismatch between reference voltage sources of different stages
Solution Approach 1:
The patent merges the reference voltage sources of the first-stage and second-stage ADCs into a single unified reference voltage source. This ensures that both stages use the same reference voltage, eliminating the gain error caused by mismatch between separate reference sources while maintaining high conversion precision and reliability
2Device complexity
If separate reference voltage sources are used for first-stage and second-stage ADCs, then device complexity is reduced, but gain error is caused by voltage mismatch between stages
Solution Approach 1:
The patent combines multiple reference voltage sources into one shared reference source that serves both the first-stage and second-stage ADCs. This merging approach maintains simple device structure while ensuring voltage consistency across stages, thereby achieving high gain accuracy without increasing complexity
Data Source
AI summary
Disclosed are an analog-to-digital conversion circuit, an analog-to-digital conversion device, and a digital x-ray imaging system. The analog-to-digital conversion circuit includes a first reference voltage source, a second reference voltage source, a first analog-to-digital converter connected to the first reference voltage source, a second analog-to-digital converter connected to the second reference voltage source, a connecting circuit connected to the first analog-to-digital converter and the second analog-to-digital converter, respectively, and a current source having negative temperature coefficient configured to be connected to the first reference voltage source and the second reference voltage source, respectively.