PCB Ground Slit Design for High-Frequency Noise Suppression
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Solution Overview
Problem
Existing printed circuit boards fail to effectively suppress the propagation of high-frequency power supply noise due to low inductance and reverse current flow through the ground wiring, which affects the functionality of semiconductor devices.
Innovation Solution
A printed circuit board design featuring a slit in the ground conductor pattern to increase the inductance of the power supply conductor pattern and enhance the bypass effect of capacitors, thereby reducing noise propagation by directing noise currents to the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply wiring is divided into two parts and a capacitor is mounted to connect across them, then the bypass performance of the capacitor is improved, but the propagation suppression effect for power supply noise remains low due to reverse current flow in the ground wiring
Solution Approach 1:
The ground conductor pattern on the second conductor layer is divided into two separate ground conductor patterns by forming a slit. This segmentation prevents the reverse current flow that occurs in the continuous ground pattern, thereby eliminating the harmful effect while maintaining the bypass performance improvement achieved by the capacitor connection.
2Device complexity
If thick and short wiring is used to connect the capacitor, then the inductance component of power supply wiring is reduced, but the fluctuations in power supply potential may adversely affect other semiconductor devices
Solution Approach 1:
By dividing the ground conductor pattern into two separate patterns using a slit, the invention creates distinct current paths that prevent noise propagation to other semiconductor devices while maintaining the low inductance characteristic of thick and short wiring connections.
3Ease of manufacture
If the ground conductor pattern is continuous, then the manufacturing process is simpler, but the inductance of the power supply conductor pattern is low and reverse current flows through the ground wiring
Solution Approach 1:
The ground conductor pattern is segmented by forming a slit, which prevents reverse current flow while adding minimal manufacturing complexity. The slit can be formed using standard PCB fabrication processes, making the solution practical and manufacturable.
4Device complexity
If the slit is not formed in the ground conductor pattern, then the ground wiring provides a low-inductance return path, but power supply noise propagates through the ground wiring in the direction reverse to the noise current
Solution Approach 1:
The slit in the ground conductor pattern segments the return path, forcing the return current to flow in a controlled manner that prevents it from carrying reverse-direction noise currents. This segmentation effectively blocks noise propagation while maintaining acceptable inductance characteristics.
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 high-frequency power supply noise propagation by increasing the inductance of the power supply conductor pattern and improving the bypass effect, ensuring stable operation of semiconductor devices.
Implementation Method 1
a capacitor including a first terminal and a second terminal... bypass capacitor very close to a semiconductor device... improve an effect of suppressing high-frequency power supply noise
Implementation Method 2
The second ground conductor pattern has a slit formed therein... increase the inductance of the power supply conductor pattern... counter-electromotive force is generated by a current flowing in the power supply wiring based on the inductance component
Data Source
AI summary
A printed wiring board includes a power supply conductor pattern arranged on one conductor layer, one ground conductor pattern arranged on the one conductor layer, and another ground conductor pattern arranged on the another conductor layer so as to be opposed to the power supply conductor pattern. The power supply conductor pattern includes a power supply pad on which a terminal of a capacitor is to be bonded. The one ground conductor pattern includes a ground pad on which another terminal of the capacitor is to be bonded. A slit is formed in the another ground conductor pattern so as to pass through a projection portion defined by projecting the power supply pad onto the another ground conductor pattern and divide a projection portion defined by projecting the power supply conductor pattern onto the another ground conductor pattern.