Filter Circuit Wiring Layout for Stable Parasitic Inductance
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Solution Overview
Problem
The parasitic inductance of capacitors in filter circuits can change due to wiring line influences, making it difficult to predict and manage noise occurrence, especially in vehicle installations where redundant circuit configurations are necessary.
Innovation Solution
A circuit device with a substrate and magnetically coupled coils, where the wiring pattern includes non-parallel third and fourth wiring lines to reduce or prevent changes in parasitic inductance, using a U-shaped third wiring line and a linear fourth wiring line to minimize magnetic coupling effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If parallel wiring lines are used to connect capacitors in a filter circuit, then the circuit layout is simple and manufacturing is easy, but the parasitic inductance changes due to magnetic coupling effects from other capacitors
Solution Approach 1:
The patent applies asymmetry by making the third wiring line have a non-parallel configuration (U-shape, L-shape, or zigzag) relative to the fourth wiring line. This asymmetric arrangement breaks the parallel alignment that causes consistent magnetic coupling, thereby stabilizing the parasitic inductance of the capacitor while maintaining manufacturing simplicity through standard PCB routing techniques.
2Area of stationary object
If the distance between current paths is reduced to minimize space, then the circuit density increases, but the parasitic inductance becomes more sensitive to wiring line influences
Solution Approach 1:
The patent employs curvature by designing the third wiring line with U-shaped, L-shaped, or zigzag patterns instead of straight lines. These curved and angular configurations reduce the parallel alignment between wiring lines carrying different currents, thereby minimizing magnetic coupling effects and stabilizing parasitic inductance even when the overall circuit footprint is compact.
3Reliability
If redundant capacitor configuration is implemented for reliability, then the circuit robustness improves, but the complexity of managing parasitic inductance increases
Solution Approach 1:
The patent applies universality by creating a wiring line configuration (particularly the non-parallel third wiring line) that simultaneously serves multiple capacitors in the redundant configuration. This single wiring pattern design benefits all capacitors by reducing their individual parasitic inductance variations, thereby simplifying the overall management of parasitic inductance across the entire redundant capacitor system.
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
This configuration effectively reduces parasitic inductance changes, improving noise reduction in a wider frequency band without requiring complex capacitor arrangements, thus simplifying manufacturing and ensuring reliable noise countermeasures.
Implementation Method 1
a negative inductance generated by magnetic coupling between two coils
Implementation Method 2
the parasitic inductance may change under the influence of the wiring line
Data Source
AI summary
A circuit device includes a substrate and a coil component including a first coil and a second coil that are magnetically coupled to each other. A wiring pattern includes a first wiring line, a second wiring line, a third wiring line on which capacitors are mounted in series, and a fourth wiring line that electrically connects the first wiring line or the second wiring line to a ground electrode. A distance between a first current path on which a current flows from the coil component to a ground electrode via the third wiring line and a second current path on which a current flows from the first wiring line or the second wiring line to the ground electrode via the fourth wiring line on which capacitors are mounted at an electrode is not constant.