Dynamic Offset Correction in AD Converters
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Solution Overview
Problem
Existing analog-to-digital converters, particularly dynamic operation type AD converters, face challenges in correcting comparator offsets, limiting their application in environments requiring constant operation such as wireless communications and industrial equipment, as static operation type AD converters cannot apply offset correction methods effectively.
Innovation Solution
A semiconductor device that determines the amount of adjustment for the comparator's offset voltage based on the offset determination result immediately after converting the least significant bit, using a sample-and-hold circuit, digital-to-analog converter, switch circuit, and comparator to dynamically adjust the offset control value in each conversion cycle, allowing for continuous offset correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a static operation type AD converter is used to correct comparator offset, then offset correction can be performed, but it cannot be applied to dynamic operation type AD converters
Solution Approach 1:
The patent transforms the static offset correction method into a dynamic one by synchronizing the correction operation with the clock signal. The correction is performed at specific timing within each conversion cycle, allowing the method to be applied to dynamic operation type AD converters while maintaining correction effectiveness
Solution Approach 2:
The offset correction is performed periodically at regular intervals synchronized with the clock signal, specifically after the least significant bit conversion. This periodic execution enables continuous offset compensation in dynamic converters without disrupting the normal conversion operation
2Ease of manufacture
If foreground operation is used to correct comparator offset, then correction can be performed once before use, but offset varies when environment changes during use
Solution Approach 1:
The patent implements continuous offset correction during the operational phase by performing correction operations periodically synchronized with the clock signal. This ensures the offset is continuously compensated as environmental conditions change, maintaining high conversion accuracy throughout the device's operational life
Solution Approach 2:
The system uses feedback from the comparator output to determine the correction amount. The correction value is adjusted based on the actual comparator offset measured during operation, creating a closed-loop system that adapts to environmental changes and maintains accuracy
3Reliability
If background operation is used to correct comparator offset, then offset can be corrected during use, but the method is limited to static operation type AD converters
Solution Approach 1:
The patent makes the background correction method dynamic by synchronizing it with the clock signal and performing corrections at specific timing within conversion cycles. This transformation allows the method to be applied to dynamic operation type AD converters while maintaining the benefits of continuous correction during operation
Data Source
AI summary
A semiconductor device according to an aspect of the invention relates to an AD converter that converts a signal level of an analog signal into a digital value by using a comparator, and determines an amount of adjustment of an offset voltage of the comparator based on an offset determination result of the comparator obtained immediately after a least significant bit (LSB) of a digital value output as a conversion result is converted.