Multilayer Multiplexer Filter Layout for Stable Inductor Characteristics
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Solution Overview
Problem
Existing multiplexers and filters in wireless communication terminals face changes in characteristics due to the presence of nearby conductors with reference potential, such as ground electrodes, leading to deteriorated inductor performance and altered filter characteristics.
Innovation Solution
A multiplexer design featuring a multilayered body with inductors and capacitors arranged to minimize the impact of nearby conductors, where the second inductor overlaps with the first inductor and has a larger ground capacitance, reducing the effect of parasitic capacitances and shield electrodes on filter characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional filter design with inductors is used, then the filter can be constructed within a multilayered body, but the characteristics change when nearby conductors with reference potential (such as ground electrodes) are present
Solution Approach 1:
A ground capacitance electrode is introduced as an intermediary element between the inductor and the ground terminal. This electrode has a larger area than the inductor's projection area and creates a controlled parasitic capacitance (Cg) that dominates over the unwanted parasitic capacitance between the inductor and nearby conductors, thereby stabilizing the filter characteristics
Solution Approach 2:
The design changes the capacitance parameter by creating a deliberate large capacitance through the ground capacitance electrode. By making the capacitance between the inductor and the ground capacitance electrode larger than the parasitic capacitance to nearby conductors, the overall electrical characteristics become less sensitive to external interference
2Device complexity
If the second inductor overlaps with the first inductor in the stacking direction, then the device complexity is reduced, but the parasitic capacitance between inductors increases
Solution Approach 1:
A dielectric layer is positioned between the first and second inductors in the overlapping region. This dielectric layer acts as an intermediary that controls and manages the parasitic capacitance between the inductors, allowing them to overlap for compactness while limiting the harmful capacitive coupling through its dielectric properties
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 reduces the change in filter characteristics due to nearby conductors, maintaining performance even when a shield electrode is present, with minimal deterioration in transmission characteristics.
Implementation Method 1
a capacitance formed between a first end of the second inductor connected to the first inductor and the ground terminal being larger than a capacitance formed between a first end of the first inductor that is closer to the common terminal along said electrical path and the ground terminal
Data Source
AI summary
A multiplexer includes: a multilayered body including dielectric layers stacked and having first and second surfaces; a common terminal, a first terminal, a second terminal, and a ground terminal disposed on a surface of the multilayered body; a first filter disposed in the multilayered body and electrically connected between the common terminal and the first terminal; a second filter including: a first inductor electrically connected between the common terminal and the second terminal; and a second inductor connected in series with the first inductor between the first inductor and the second terminal, the second inductor at least partially overlapping with the first inductor, a capacitance between a first end of the second inductor electrically closer to the common terminal and the ground terminal being larger than a capacitance between a first end of the first inductor electrically closer to the common terminal and the ground terminal.