Acoustic Wave Multiplexer Layout for Precise Impedance Matching
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Solution Overview
Problem
Existing multiplexers with inductance elements connected to common terminals struggle with accurate impedance matching between acoustic wave filters and external circuits, often shifting combined impedance to the capacitive side, making it difficult to achieve a reference impedance.
Innovation Solution
A multiplexer design with multiple acoustic wave filters connected to a common terminal, where an inductance element is strategically placed between a wiring line extending from the common terminal and ground, allowing for precise impedance matching by adjusting the phase and impedance of the filters to align with a reference impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inductance element is connected to the common terminal closer to the terminal than the filters, then circuit connection is established, but impedance matching accuracy deteriorates because the combined impedance shifts to the inductive side
Solution Approach 1:
A capacitor is introduced as an intermediary element between the inductance element and the acoustic wave filters. This capacitor acts as a mediator that counteracts the inductive reactance introduced by the inductance element, enabling accurate impedance matching. The capacitor's capacitive reactance compensates for the inductive shift, allowing the combined impedance to be brought close to the reference impedance while maintaining proper circuit connection.
2Device complexity
If the inductance element is positioned closer to the common terminal, then circuit connection is simplified, but the combined impedance of the filters shifts to the capacitive side making it difficult to achieve reference impedance
Solution Approach 1:
The invention changes the electrical parameters of the circuit by introducing a capacitor with specific capacitance value. This parameter change (adding capacitive reactance) counteracts the inductive reactance effect, allowing the overall impedance to be adjusted to match the reference impedance. The capacitor's parameters are selected to achieve the desired impedance matching while maintaining circuit simplicity.
3Reliability
If acoustic wave filters with capacitive impedance are used, then filter performance is achieved, but the combined impedance shifts further to the capacitive side requiring additional inductance for matching
Solution Approach 1:
The capacitor serves as an intermediary that directly addresses the capacitive impedance shift caused by the acoustic wave filters. By positioning the capacitor between the inductance element and the filters, it creates a balanced impedance network where the capacitive and inductive reactances compensate for each other, simplifying the overall impedance matching process while maintaining filter 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 design enables high-accuracy impedance matching with external circuits, reducing propagation loss and allowing for a significant size reduction of the multiplexer while maintaining low dielectric loss, thereby improving performance in multi-band and multi-mode communication applications.
Implementation Method 1
perform impedance matching between the acoustic wave filters and an external circuit connected to the common terminal
Implementation Method 2
an inductance element connected between a wiring region of the first wiring line that extends from the first connection node to the first acoustic wave filter and a ground or between the second wiring line and the ground
Implementation Method 3
a multiplexer that includes an acoustic wave filter
Implementation Method 4
demultiplexes/multiplexes high frequency signals of a plurality of communication bands
Data Source
AI summary
A multiplexer includes a common terminal, a first filter connected to the common terminal, a wiring line connecting the common terminal and the reception filter to each other, a second filter connected to a connection node on the wiring line, a third filter connected to a connection node on the wiring line, a wiring line connecting the connection node and the transmission filter to each other, a wiring line connecting the connection node and the first filter to each other, and an inductor connected between a wiring region of the wiring line that extends from the connection node to the first filter and the ground or between the wiring line and the ground. The length of a portion of the wiring line extending from the common terminal to the connection node is longer than the length of a portion of the wiring line extending from the common terminal to the connection node.