DC-DC Converter Module Noise Suppression via Ground Segmentation
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Solution Overview
Problem
Existing DC-DC converter modules suffer from high noise levels due to high wiring impedance and noise coupling between the switching IC and coil, which affects the ground potential and output noise characteristics.
Innovation Solution
The solution involves connecting the coil's end closer to the second surface to the switching IC's input or output electrode on a multi-layer substrate, with a shield layer formed of a ground electrode between the first and second surfaces, and a capacitor connected between the coil and ground terminal, to directly couple the wiring line and ground terminal, thereby suppressing common impedance noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the wiring line connects the ground electrode to the switching IC through the magnetic substrate, then the module structure is simplified, but the wiring impedance increases and ground potential stability deteriorates
Solution Approach 1:
The patent segments the ground connection path by providing separate ground terminals (first ground terminal and second ground terminal) for different functional areas. The first ground terminal connects to the ground electrode near the coil, while the second ground terminal connects to the switching IC ground port, creating independent ground paths that prevent noise coupling and maintain stable ground potential throughout the module.
2Volume of moving object
If the wiring line between switching IC and coil is placed near the ground port, then the module size is reduced, but noise transmission increases due to coupling between the wiring line and ground port
Solution Approach 1:
The patent extracts the noisy wiring line (carrying saw tooth or pulse current) from proximity to the ground port by positioning it near the first ground terminal instead. This spatial separation removes the harmful electromagnetic coupling between the high-current wiring line and the ground port, preventing noise transmission while maintaining compact module dimensions through optimized layout.
3Object-affected harmful factors
If a shield layer is added between the first surface and coil layers, then noise characteristics are improved, but device complexity increases
Solution Approach 1:
The patent makes the first ground terminal serve multiple functions: it acts as both a ground connection point for the coil and as a shield layer between the switching IC and the coil. This ground terminal at the first surface position provides electromagnetic shielding against noise coupling while simultaneously establishing a stable ground reference, eliminating the need for a separate shield layer structure.
Data Source
Figure 1~2A
Figure 2B~2C
Figure 2D~3A
AI summary
Provided is a DC-DC converter module having good noise characteristics. A DC-DC converter module (1) includes a multi-layer substrate (5), a switching IC (2), and a coil (4). The multi-layer substrate (5) includes component mounting electrodes provided on the top surface and an input terminal, an output terminal, and ground terminals (GND1, GND2) provided on the bottom surface. The switching IC (2) switches an input voltage and includes an input electrode, an output electrode, and a ground electrode, and is mounted on the top surface of the substrate by connecting the electrodes to the component mounting electrodes. The coil (4) is formed within the multi-layer substrate (5) in a spiral shape with an axis in the substrate stacking direction. The bottom surface side end of the coil (4) is connected to the input/output electrode of the switching IC (2).