Diplexer Loop Inductor Layout for Low-Loss Filter Isolation
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Solution Overview
Problem
The complexity in routing conductors within diplexers, particularly when outer electrodes are formed only on the bottom surface, leads to increased insertion loss and degraded characteristics due to interference between high-band-side and low-band-side filters.
Innovation Solution
A diplexer design with a multilayer body featuring loop inductors and via hole conductors that connect input/output terminals to filter circuits, allowing for simplified conductor routing by positioning loop planes to avoid overlap and reduce electromagnetic coupling between filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If outer electrodes are formed only on the bottom surface of the multilayer body, then the surface area of the mounting region becomes smaller, but the routing of wiring lines inside the diplexer becomes complex
Solution Approach 1:
The patent utilizes the stacking direction (vertical dimension) of the multilayer body to route via hole conductors, allowing wiring lines to connect outer electrodes on the bottom surface to filter circuits without increasing planar footprint. By distributing conductor layers across multiple stacking directions and layers, the design achieves complex routing functionality while maintaining a compact mounting region.
2Object-affected harmful factors
If via hole conductors are routed to connect LB-side filter to outer electrode while avoiding HB-side filter overlap, then electromagnetic interference is reduced, but routing becomes complex and insertion loss increases
Solution Approach 1:
The patent divides the diplexer into distinct high-band-side and low-band-side filter regions with separated conductor layer configurations. By segmenting the wiring routing paths for each filter type and using different layer combinations (e.g., first through fourth conductor layers for HB-side, first through third conductor layers for LB-side), the design minimizes electromagnetic interference while maintaining manageable routing complexity.
Solution Approach 2:
The patent resolves routing conflicts by utilizing the vertical stacking dimension, allowing via hole conductors to pass through intermediate layers without horizontal overlap with opposing filter circuits. This three-dimensional routing approach enables interference-free connections without requiring excessively complex planar routing patterns.
3Object-affected harmful factors
If complex routing is used to avoid filter interference, then electromagnetic coupling is reduced, but insertion loss increases due to extra wiring lines
Solution Approach 1:
The patent merges multiple conductor layers into shared ground and signal paths where possible, reducing the total number of discrete wiring lines required. By combining routing functions across layers and utilizing common via hole conductor paths for multiple filter connections, the design minimizes the cumulative insertion loss that would result from numerous separate routing traces while maintaining electromagnetic isolation.
Data Source
AI summary
A diplexer includes a first filter circuit including a first loop inductor defining a first loop plane and a second loop inductor defining a second loop plane, a second filter circuit adjacent to the first filter circuit, and a first via hole conductor that electrically connects an input/output terminal, the first filter circuit and the second filter circuit to each other. The first loop plane faces the second loop plane while protruding beyond the second loop plane in a first direction. The first via hole conductor is provided relative to the first loop inductor in a second direction from the first loop plane toward the second loop plane, and is superposed with a portion of the first loop plane that protrudes beyond the second loop plane when viewed in the second direction.