Dual-Gain ADC Circuit for Stable Current Measurement Switching
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Solution Overview
Problem
Analog-to-digital conversion circuits with variable gain amplifiers experience phase lag and delayed stabilization during gain changes, leading to incorrect measurements until the output signal stabilizes, which increases the waiting time for accurate measurement.
Innovation Solution
The implementation of a dual variable gain amplifier system with a control circuit that manages the gain change periods of both amplifiers in a relative manner, ensuring non-overlapping gain change periods and allowing for immediate correct measurement values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable gain amplifier is used to expand the dynamic range of the AD converter, then the dynamic range is improved, but the measurement accuracy deteriorates during gain change due to phase lag and delayed stabilization
Solution Approach 1:
The patent divides the single AD conversion system into two parallel AD converters, each with its own variable gain amplifier. This segmentation allows one converter to be in gain change mode while the other maintains stable operation, thereby resolving the contradiction between dynamic range adaptability and measurement precision during transitions.
Solution Approach 2:
The control circuit预先 determines the timing of gain changes for both variable gain amplifiers to ensure their gain change periods do not overlap. By planning gain changes in advance and staggering them, the system maintains at least one stable measurement channel at all times, preventing simultaneous measurement degradation.
2Adaptability or versatility
If the gain of the variable gain amplifier is changed to adapt to varying current levels, then the adaptability is improved, but the waiting time for accurate measurement increases
Solution Approach 1:
The patent ensures continuous accurate measurement capability by maintaining two parallel measurement channels. While one channel undergoes gain change, the other continues providing accurate measurements. This continuity eliminates the waiting time that would otherwise be required for gain stabilization, as the system never loses measurement capability.
Solution Approach 2:
The control circuit预先 coordinates gain change timing to stagger transitions between the two variable gain amplifiers. By planning gain changes in advance and ensuring they occur at different times, the system prepares for gain transitions without interrupting measurement operations, thereby reducing waiting time.
3Reliability
If two or more AD converters are used for redundant current measurement, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges two AD conversion systems into a unified architecture where both converters share common components such as the input terminal, selection circuit, and control circuit. This merging approach achieves the reliability benefits of redundant measurement while minimizing the increase in device complexity through resource sharing.
Solution Approach 2:
The control circuit performs multiple functions: it controls the gain of both variable gain amplifiers, manages the timing coordination to prevent overlapping gain changes, and directs the selection circuit to choose between the two AD converter outputs. This multi-functionality reduces the need for separate control mechanisms, thereby limiting complexity growth.
Data Source
AI summary
An analog-to-digital conversion circuit includes: a first variable gain amplifier connected to an input terminal; a first AD converter connected to the first variable gain amplifier; a second variable gain amplifier connected to the input terminal; a second AD converter connected to the second variable gain amplifier; a selection circuit to which an output of the first AD converter and an output of the second AD converter are input, and which selects one of the outputs; and a control circuit that controls a gain change period of the first variable gain amplifier and a gain change period of the second variable gain amplifier in a relative manner.