Switching Power Supply PCB Layout for Common-Mode Noise Cancellation
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Solution Overview
Problem
Existing technologies fail to address the issue of electromagnetic interference (EMI) and common-mode noise in switching power supplies, particularly in DC-DC converters, resulting in unwanted size and inefficiency.
Innovation Solution
A switching power supply including a switching element for power conversion, with an input capacitor, a first switching element, a second switching element, an inductor, an output capacitor, and a circuit board, the first wiring pattern, and a reference potential pattern, the first wiring pattern, the second wiring pattern, and a reference potential pattern, the first wiring pattern, the second wiring pattern, and a reference potential pattern, the first wiring pattern, the second wiring pattern, the third wiring pattern, and a noise-balancing circuit formed by a closed electric circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield member is added to reduce switching noise radiation, then electromagnetic interference is reduced, but the device size increases
Solution Approach 1:
The patent extracts the noise reduction function from a separate shield member and integrates it into the existing circuit components. The inductor's parasitic capacitance and the circuit board's wiring patterns are utilized to create a noise-balancing circuit that cancels electromagnetic noise without requiring additional shield components, thereby reducing device size while maintaining EMI reduction effectiveness.
Solution Approach 2:
The patent makes existing components serve multiple functions: the inductor not only performs power conversion but also provides noise cancellation through its parasitic capacitance; the wiring patterns not only connect components but also form part of the noise-balancing circuit. This multi-functionality eliminates the need for dedicated shield members while maintaining both power conversion and EMI reduction capabilities.
2Object-affected harmful factors
If a shield member is added to reduce switching noise radiation, then common-mode noise is reduced, but device complexity increases
Solution Approach 1:
The patent enables the circuit to self-cancel its own noise through the noise-balancing circuit formed by existing components. The parasitic capacitance of the inductor and the wiring patterns work together to generate counter-phase noise that automatically cancels common-mode noise without requiring external control or additional active components, thereby reducing device complexity.
3Object-affected harmful factors
If wiring patterns are optimized to form a noise-balancing circuit, then electromagnetic noise is canceled, but manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes the inherent parasitic capacitance parameter of the inductor, which varies based on its construction, to create the noise-balancing circuit. By designing the circuit to work with the inductor's natural electrical characteristics rather than requiring precise geometric positioning, the manufacturing precision requirements are reduced while maintaining noise cancellation effectiveness.
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 switching power supply effectively cancels electromagnetic noise and reduces common-mode noise radiation or conduction without additional noise reduction components, achieving high efficiency and compact size.
Implementation Method 1
The inductor has, between the first terminal and the second terminal, an internal parasitic capacitance of the inductor due to construction of the winding conductor and the magnetic core
Data Source
AI summary
A circuit board includes first and second wiring patterns and a reference-potential-side wiring pattern. The first wiring pattern electrically connects a node between first and second switching elements, and a first terminal to each other. The second wiring pattern electrically connects a second terminal and an output capacitor to each other. In plan view of the circuit board, the first wiring pattern has an area smaller than an area of the second wiring pattern. The inductor has a parasitic capacitor between the first and second terminals due to the construction of a winding conductor and a magnetic core. Due to the positioning of the circuit board with respect to a chassis, at the switching frequency of the first and second switching elements, the parasitic capacitor of the inductor is greater in capacitance than a parasitic capacitor between the magnetic core and the chassis.