Operational Amplifier Circuit with Input Offset Voltage Polarity Control
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Solution Overview
Problem
Conventional operational amplifier circuits face issues with input offset voltage polarity changes due to temperature or package sealing, leading to current detection errors as they cannot maintain a constant polarity, affecting the accuracy of current detection.
Innovation Solution
An operational amplifier circuit with a potential control circuit and an input offset voltage polarity determination unit that controls the output potential of the current sense semiconductor element to match the main semiconductor element's potential, and uses a selector circuit to adjust the input terminals based on the polarity determination, ensuring constant input offset voltage polarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the output potential of the current sense semiconductor element and the output potential of the main semiconductor element are input to the operational amplifier to control the current-limiting semiconductor element, then the current detection function is achieved, but the input offset voltage polarity changes due to temperature or package sealing, causing current detection errors
Solution Approach 1:
The patent applies preliminary action by determining the polarity of the input offset voltage before it causes detection errors. The polarity determination unit identifies whether the offset voltage is positive or negative in advance, and the selector circuit pre-configures the appropriate feedback path to compensate for this offset, ensuring accurate current detection from the start of operation.
Solution Approach 2:
The patent implements feedback by using the polarity determination unit to continuously monitor the input offset voltage polarity and dynamically switching the feedback configuration through the selector circuit. This feedback mechanism ensures that the operational amplifier operates with the correct compensation regardless of temperature changes or package sealing variations, maintaining reliable current detection.
2Measurement precision
If adjustment is made to a reference voltage of a comparator to eliminate influence of the input offset voltage, then the current detection accuracy is improved, but the polarity of the input offset voltage may change between positive and negative polarities due to temperature or package sealing, causing detection errors
Solution Approach 1:
The patent applies dynamics by making the feedback configuration adaptive rather than fixed. The selector circuit dynamically switches between different feedback paths based on the real-time polarity of the input offset voltage, allowing the system to adapt to temperature changes and package sealing variations without requiring manual recalibration or sacrificing detection accuracy.
Solution Approach 2:
The patent implements parameter changes by modifying the feedback configuration parameters based on the detected input offset voltage polarity. When the polarity changes from positive to negative or vice versa, the system changes the feedback path parameters accordingly, ensuring that the operational amplifier maintains optimal performance across varying operating conditions.
3Device complexity
If the conventional technology is used without polarity control, then the device complexity is reduced, but the current detection error becomes large due to the changed input offset voltage
Solution Approach 1:
The patent applies universality by designing the operational amplifier circuit to perform multiple functions: standard amplification and offset voltage compensation. The selector circuit and polarity determination unit enable the same circuit to automatically adapt to different offset voltage conditions without requiring separate compensation circuits, maintaining relatively simple overall structure while improving detection accuracy.
Data Source
AI summary
An operational amplifier circuit includes a potential control circuit connected between a current sense semiconductor element connected in parallel with a main semiconductor element and a current detection resistor. The potential control circuit controls an output potential of the current sense semiconductor element to be equal to that of the main semiconductor element. The potential control circuit includes a current control element controlling an output current of the current sense semiconductor element and an operational amplifier outputting a signal corresponding to an output potential difference between the current sense semiconductor element and the main semiconductor element to the current control element. An input offset voltage polarity determination unit determines a polarity of an input offset voltage of the operational amplifier according to the output potential difference. The polarity of the input offset voltage is controlled to be constant based on polarity determination of the input offset voltage.