Duplexer Stub Coupling Layout for Better Filter Isolation
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Solution Overview
Problem
Existing duplexers in communication devices face challenges in improving isolation characteristics between transmit and receive filters, leading to signal leakage and reduced flexibility in wiring arrangements.
Innovation Solution
The duplexer design incorporates open and short stubs that are electromagnetically coupled, allowing for improved isolation characteristics between filter circuits while increasing the flexibility in wiring arrangements by adjusting the self-inductance values and overlapping amounts of these stubs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first and second wirings are arranged in parallel to improve isolation characteristics, then the isolation between transmit and receive filters is improved, but the flexibility in wiring arrangement is reduced
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement where wirings must be parallel to a three-dimensional stacked arrangement where wirings can be positioned above or below each other. This vertical stacking enables electromagnetic coupling for isolation while providing greater spatial freedom and flexibility in the wiring layout.
Solution Approach 2:
The patent introduces a ground wiring as an intermediary element between the first and second wirings. This ground wiring serves as a reference potential that enables electromagnetic coupling between the signal wirings, improving isolation characteristics while allowing more flexible arrangement of the signal paths.
2Reliability
If the first wiring is connected to the common terminal and opened at the other end, then the isolation characteristics are improved, but the impedance characteristics may be affected
Solution Approach 1:
The patent adjusts the physical parameters of the open-ended first wiring, including its length, width, and position relative to the ground wiring, to optimize both isolation characteristics and impedance matching. By carefully controlling these geometric parameters, the design achieves high isolation while maintaining proper impedance characteristics.
Solution Approach 2:
The patent applies different structural configurations to different parts of the wiring system. The first wiring has an open end with specific dimensional characteristics, while the second wiring has a grounded end, creating localized variations in electrical properties that collectively achieve both isolation and impedance control.
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
This configuration enhances the isolation characteristics between filter circuits, reducing signal leakage and allowing for more flexible and efficient design of duplexer structures without significantly affecting impedance characteristics.
Implementation Method 1
The first and second wirings are electromagnetically coupled with each other
Data Source
AI summary
A duplexer includes first and second filter circuits and first and second wirings. The first filter circuit allows a signal of a first frequency band to pass therethrough between a first terminal and a common terminal and includes a first resonator which is connected at one end to a line disposed between the first terminal and the common terminal to branch off from the line. The second filter circuit allows a signal of a second frequency band, which is different from the first frequency band, to pass therethrough between a second terminal and the common terminal. The first wiring is connected at one end to the common terminal and is opened at the other end. The second wiring is connected at one end to the other end of the first resonator and is grounded at the other end. The first wiring is electromagnetically coupled with second wiring.