Elastic Wave Filter Substrate Layout for Better Isolation
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Solution Overview
Problem
Elastic wave filter apparatuses with ladder circuit configurations face challenges in improving isolation characteristics without increasing loss, as adjusting electrode shapes to enhance isolation often results in increased loss.
Innovation Solution
The elastic wave apparatus includes a mounting substrate with an inductor connected between parallel arm resonators and ground potential, featuring a signal wiring at a different height and a ground wiring at an intermediate height, with a slit in the ground wiring overlapping the inductor, allowing for improved isolation characteristics without increased loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode shape is adjusted to improve isolation characteristics, then the isolation characteristics are improved, but the loss increases
Solution Approach 1:
The patent introduces a ground wiring at an intermediate height position between the inductor and signal wiring, creating a three-dimensional layered structure. This dimensional addition provides a new pathway for electromagnetic field management without altering the traditional two-dimensional electrode layout, thereby improving isolation characteristics without increasing loss
Solution Approach 2:
The ground wiring acts as an intermediary element between the inductor and signal wiring. By positioning it at an intermediate height, it mediates the electromagnetic interaction between these components, providing shielding and field control that improves isolation while maintaining low loss through optimized field distribution
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 effectively enhances isolation characteristics while maintaining low loss, as demonstrated by improved bandpass and isolation characteristics in the elastic wave apparatus, particularly in the reception band of Band 26.
Implementation Method 1
an inductor which is connected between at least one of the parallel arm resonators and a ground potential
Implementation Method 2
series arm resonators and parallel arm resonators each of which is defined by an elastic wave resonator
Data Source
AI summary
An elastic wave apparatus includes first and second bandpass filters and the first bandpass filter is a ladder elastic wave filter. The mounting substrate includes an inductor which is connected between at least one of parallel arm resonators and a ground potential, a signal wiring at a hot side, which is connected to the first bandpass filter, and a ground wiring. When the mounting substrate is viewed from a side of a surface on which the elastic wave filter chip is mounted, a portion of the inductor overlaps with a portion of the signal wiring and a slit defining a wiring missing portion in which the ground wiring is absent in the ground wiring is provided in the overlapped portion.