PCB Capacitor Layout for Radiation Noise Cancellation
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Solution Overview
Problem
Circuit boards induce radiation noise due to closed circuits, which causes electromagnetic interference (EMI) affecting nearby electronic equipment, and existing noise filters do not effectively reduce this radiation noise.
Innovation Solution
A circuit board design featuring a stack of conductive layers with insulating layers in between, including first and second capacitors that form closed circuits with opposite magnetic field orientations, reducing radiation noise by offsetting induced magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a closed circuit is formed for bypass capacitor connection, then conduction noise is reduced, but radiation noise is generated due to induced magnetic field
Solution Approach 1:
The bypass capacitor connection is segmented into multiple separate connection points (first and second connection points) on the power supply wiring pattern. This segmentation creates multiple smaller closed circuits instead of one large closed circuit, reducing the overall area and thus the radiation noise while maintaining the conduction noise filtering function.
Solution Approach 2:
The bypass capacitors are connected at specific local positions (both ends of the semiconductor device in the signal transmission direction) rather than at a single central point. This local quality approach distributes the magnetic field induction locally, allowing the fields to cancel each other out and reducing overall radiation noise.
2Object-affected harmful factors
If bypass capacitors are connected to form closed circuits, then noise filtering is achieved, but the area enclosed by the circuits increases radiation noise
Solution Approach 1:
The single large closed circuit is segmented into multiple smaller closed circuits by connecting bypass capacitors at different locations (both ends of the semiconductor device). This segmentation reduces the total area enclosed by the circuits, thereby reducing the induced magnetic field strength and radiation noise while maintaining effective noise filtering.
3Device complexity
If a single bypass capacitor is used, then circuit complexity is low, but noise reduction effectiveness is insufficient
Solution Approach 1:
Instead of using a single bypass capacitor, the invention uses multiple bypass capacitors connected at different points (both ends of the semiconductor device). This segmentation approach increases noise reduction effectiveness by creating multiple noise filtering paths and reducing the area of individual closed circuits, while the overall configuration remains relatively simple.
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
The design effectively suppresses radiation noise by ensuring induced magnetic fields from the closed circuits counteract each other, reducing noise intensity in all directions and minimizing the area enclosed by these circuits, thus reducing electromagnetic interference.
Implementation Method 1
the induced magnetic field (hereinafter referred to as 'first induced magnetic field') generated in the first closed circuit and the induced magnetic field (hereinafter referred to as 'second induced magnetic field') generated in the second closed circuit have mutually opposite directions
Data Source
AI summary
In a circuit board (700A), a first capacitor (410) extends from a wiring pattern (110) to a region located on one side of the wiring pattern (110) in the width direction. A second capacitor (420) extends from the wiring pattern (110) to a region located on the other side of the wiring pattern (110) in the width direction. With a semiconductor device (300) mounted on the circuit board (700A), a power supply terminal (320) is electrically connected to the wiring pattern (110). The semiconductor device (300), the wiring pattern (110), the first capacitor (410), a first interlayer joint (510), a ground plane (210), and a third interlayer joint (530) constitute a first closed circuit. The semiconductor device (300), the wiring pattern (110), the second capacitor (420), a second interlayer joint (520), the ground plane (210), and the third interlayer joint (530) constitute a second closed circuit.