Acoustic Wave Multiplexer Layout for Low-Capacitance Antenna Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multiplexers face challenges in achieving impedance matching between an antenna element and a common connection terminal due to capacitance generated between wiring and ground, leading to increased insertion loss, especially as the number of acoustic wave filters increases.
Innovation Solution
The design includes at least three acoustic wave filters with specific resonator configurations and inductance elements connected in series and parallel, with the antenna terminals of second acoustic wave filters being connected closer to the antenna connection terminal to reduce wiring length and capacitance, and utilizing a laminated piezoelectric substrate structure to maintain high Q values and low insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of acoustic wave filters connected to the common connection terminal is increased, then the multi-band and multi-mode operation capability is improved, but the capacitance generated between wirings and ground increases, making impedance matching more difficult and deteriorating insertion loss
Solution Approach 1:
The patent transitions from a planar wiring layout to a three-dimensional stacked configuration. Acoustic wave filters are arranged in multiple layers above the substrate, with wirings routed through vertical vias and horizontal connection lines. This spatial reorganization reduces the surface area of wirings exposed to ground capacitance, thereby reducing parasitic capacitance effects while maintaining support for multiple frequency bands and modes.
Solution Approach 2:
The patent divides the wiring path into multiple segmented sections: vertical via connections from upper layer filter terminals to lower layer connection points, horizontal connection lines on intermediate layers, and final connections to the common connection terminal. This segmentation allows optimization of each wiring segment's length and positioning, reducing total parasitic capacitance while maintaining electrical connectivity for multiple filters.
2Ease of manufacture
If the length of wirings connecting acoustic wave filters to the common connection terminal is increased, then the layout flexibility is improved, but the capacitance between wirings and ground increases, deteriorating insertion loss
Solution Approach 1:
The patent utilizes vertical stacking to reduce horizontal wiring lengths. Filters in upper layers connect to the common terminal through short vertical via paths and compact horizontal connections on intermediate layers, rather than long horizontal traces on a single plane. This three-dimensional routing maintains layout flexibility while minimizing parasitic capacitance and insertion loss.
3Reliability
If inductance elements are added to achieve impedance matching, then the impedance matching capability is improved, but the device complexity increases
Solution Approach 1:
The patent combines the inductance element with existing structural components. The inductance element is integrated into the connection path between acoustic wave filters and the common connection terminal, sharing the same physical space and mounting structure. This merging approach provides impedance matching functionality without adding separate discrete components, thereby reducing overall device complexity while maintaining matching performance.
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 reduces capacitance and insertion loss in the pass band of acoustic wave filters, improving impedance matching and high-frequency transmission characteristics.
Implementation Method 1
each of the at least three acoustic wave filters includes, on a piezoelectric substrate, at least one of a serial arm resonator connected between an input terminal and an output terminal, and a parallel arm resonator connected between a reference terminal and a connection path connecting the input terminal and the output terminal
Implementation Method 2
an inductance element for achieving impedance matching between the antenna element and the common connection terminal is connected in series
Data Source
AI summary
In a multiplexer, input or output terminals of four acoustic wave filters are connected to, among a plurality of terminals provided on piezoelectric substrates, antenna terminals connected to an antenna connection terminal; the four acoustic wave filters include a first acoustic wave filter and a second acoustic wave filter that is located at a farther position from the antenna connection terminal than a position of the first acoustic wave filter in a plan view of a substrate; and among the plurality of terminals, the terminals located at the closest position to the antenna connection terminal in the plan view of the substrate are connected to the second acoustic wave filter as the antenna terminals.