Differential Detection Circuit Layout for Electromagnetic Noise Cancellation
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Solution Overview
Problem
Conventional current detection circuits using shunt resistors and differential amplifiers are prone to interference from electromagnetic noise, requiring additional components and circuit area, increasing manufacturing costs and reducing detection accuracy.
Innovation Solution
A detection circuit design that includes parallel detection wires arranged to cancel out induced voltages from electromagnetic noise, using a differential amplifier to combine and neutralize interference, without adding extra components or circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two current detection circuits are provided to cancel electromagnetic noise, then detection accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent segments the detection wires into multiple parallel wires (first detection wire and second detection wire) connected to the same differential amplifier. This segmentation allows the circuit to process multiple signal paths simultaneously while using a single amplifier, reducing overall circuit complexity compared to using separate amplifiers for each detection path.
Solution Approach 2:
The patent merges multiple detection wires (first and second detection wires) into a single differential amplifier input structure. By combining the signal processing function into one amplifier rather than using separate amplifiers for each detection path, the circuit reduces component count and complexity while maintaining the ability to cancel electromagnetic noise through differential processing.
2Measurement precision
If two current detection circuits are provided to cancel electromagnetic noise, then detection accuracy is improved, but circuit area increases
Solution Approach 1:
The patent merges multiple detection wires into a single differential amplifier, eliminating the need for separate amplifier circuits that would occupy additional board space. This consolidation reduces the overall circuit area while maintaining noise cancellation capability through the differential amplifier's inherent rejection of common-mode electromagnetic interference.
3Device complexity
If shunt resistor is used for current detection, then circuit configuration is simplified, but electromagnetic noise interference occurs
Solution Approach 1:
The patent converts the harmful effect of electromagnetic noise into a beneficial differential signal. By using a differential amplifier with multiple parallel detection wires, the circuit allows electromagnetic noise to induce voltages that are then differentially processed and canceled out. The same wiring structure that picks up noise also provides the differential paths needed to reject it, turning the noise-coupling wires into noise-rejection elements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurately detects current or voltage while reducing interference from electromagnetic noise, maintaining detection accuracy without increasing component count or circuit size.
Implementation Method 1
The first detection wire and the second detection wire are arranged in the electric circuit so as to, by induced voltages generated due to external electromagnetic noise, cancel out induced voltages generated on the plus-side detection wire and the minus-side detection wire due to the electromagnetic noise
Data Source
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AI summary
A detection circuit (1) includes: a differential amplifier (4) which outputs voltage according to current or voltage detected by a detector (3) interposed on a path in an electric circuit; a plus-side detection wire (5a) connected between a plus input terminal of the differential amplifier (4) and one end of both ends of the detector; a minus-side detection wire (5b) connected between a minus input terminal of the differential amplifier and another end of both ends; at least one first detection wire (5c) connected in parallel to at least a part of the plus-side detection wire between the one end of the detector and the plus input terminal of the differential amplifier; and at least one second detection wire (5d) connected in parallel to at least a part of the minus-side detection wire between the other end of the detector and the minus input terminal of the differential amplifier. The first detection wire and the second detection wire are arranged in the electric circuit so as to, by induced voltages generated due to electromagnetic noise, cancel out induced voltages generated on the plus-side detection wire and the minus-side detection wire due to the electromagnetic noise.