PCB Planar Capacitor Noise Reduction
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Solution Overview
Problem
Conventional printed circuit boards are insufficient in reducing electromagnetic radiation noise, particularly at high frequencies, due to limitations in the configuration of power source conductor planes and capacitors, which allows noise current to leak and propagate, leading to malfunctions and regulatory compliance issues.
Innovation Solution
A printed circuit board design featuring a multilayer configuration with separated power source conductor planes and a planar capacitor formed between the second power source conductor plane and the ground conductor plane, along with a capacitor element connected to the power source and ground terminals, to efficiently direct noise current to the ground and reduce electromagnetic radiation noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the power source conductor plane is separated into multiple planes (first and second power source conductor planes), then the electromagnetic radiation noise is reduced, but the device complexity increases
Solution Approach 1:
The power source conductor plane is segmented into a first power source conductor plane and a second power source conductor plane that are separated from each other. This segmentation prevents noise current generated by the semiconductor device from propagating through a continuous power source plane, thereby reducing electromagnetic radiation noise while maintaining the necessary electrical connections through dedicated via conductors.
2Object-generated harmful factors
If the second power source conductor plane is arranged to face the ground conductor plane to form a planar capacitor, then the noise current is directed to ground, but the inductance between power source planes increases
Solution Approach 1:
A planar capacitor is formed as an intermediary structure between the second power source conductor plane and the ground conductor plane. This planar capacitor provides a low-impedance path for noise current to reach ground, effectively directing noise current away from propagating through the first power source conductor plane, while the via conductors maintain necessary power source connections.
3Object-generated harmful factors
If conventional capacitor configuration is used, then the noise reduction is insufficient at high frequencies, but increasing capacitance may increase device complexity
Solution Approach 1:
The invention transitions from using only discrete capacitors to utilizing the third dimension by forming a planar capacitor within the multilayer board structure itself. The planar capacitor is created by arranging the second power source conductor plane to face the ground conductor plane across a dielectric layer, providing effective high-frequency noise reduction through the capacitive coupling in the vertical dimension without adding external components.
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 reduces electromagnetic radiation noise by increasing the inductance between power source conductor planes and directing noise current directly to the ground, thereby minimizing noise propagation and compliance with electromagnetic radiation regulations, especially in high-frequency bands.
Implementation Method 1
a planar capacitor formed by the second power source conductor plane and the ground conductor plane
Data Source
AI summary
A printed circuit board includes a printed circuit board, a semiconductor device mounted on the printed circuit board, a capacitor element mounted on the printed circuit board 2, a ground conductor plane to which a ground terminal of the semiconductor device is connected, and first and second power source conductor planes which are arranged so as not to contact with each other. The second power source conductor plane and the ground conductor plane are arranged so as to oppose to each other to form a planar capacitor. The printed circuit board has a first connecting conductor which connects a power source terminal of the semiconductor device with the second power source conductor plane, and a second connecting conductor which connects the first power source conductor plane with the second power source conductor plane through a first terminal of the capacitor element. Thereby, an electromagnetic radiation noise is reduced.