Multiplexer Impedance Matching With Series Acoustic Wave Resonator
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Solution Overview
Problem
Existing multiplexers fail to optimize the impedance of filters connected to a common terminal and other filters simultaneously, leading to suboptimal bandpass characteristics due to the use of passive elements with fixed circuit constants.
Innovation Solution
A multiplexer design that includes a first common terminal, input/output terminals, filters with different passbands, and an impedance matching circuit with a series-connected acoustic wave resonator, allowing for individual optimization of impedance in both the passband and attenuation band of the filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a passive element with fixed circuit constant (capacitor or inductor) is disposed between common terminal and filter, then the impedance of the filter changes uniformly over wide band, but both optimization of bandpass characteristics of the filter and optimization of bandpass characteristics of other filters cannot be achieved simultaneously
Solution Approach 1:
The patent applies the dynamics principle by replacing static passive elements (fixed capacitor or inductor) with a dynamic impedance matching circuit comprising variable impedance elements. This circuit can dynamically adjust its impedance characteristics to optimize both the bandpass filter's passband and the other filters' passbands simultaneously, resolving the contradiction between adaptability and complexity.
Solution Approach 2:
The patent implements parameter changes by using an impedance matching circuit whose impedance parameters can be varied to achieve optimal performance. The circuit includes elements that can change their electrical parameters (impedance magnitude and phase) to simultaneously optimize multiple filter passbands, transforming the fixed-parameter approach into a variable-parameter solution.
2Ease of manufacture
If multiple filters are connected to common terminal with fixed passive elements, then simple circuit structure is achieved, but impedance optimization in attenuation bands and passbands cannot be achieved simultaneously
Solution Approach 1:
The patent introduces an impedance matching circuit as an intermediary component between the common terminal and the filters. This intermediary element mediates the impedance relationships, enabling precise control over the impedance characteristics seen by each filter while maintaining a relatively simple overall circuit structure that is easier to manufacture with precise 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
Enables simultaneous optimization of bandpass characteristics of multiple filters, improving insertion loss and attenuation characteristics, allowing for efficient transmission and reception of radio-frequency signals across different frequency bands.
Implementation Method 1
an impedance matching circuit disposed between the first common terminal and the second filter. The impedance matching circuit includes a first acoustic wave resonator that is disposed in series on a path connecting the first common terminal to the second filter
Data Source
AI summary
A multiplexer includes a common terminal, a first reception output terminal, a second reception output terminal, a first filter that is connected between the common terminal and the first reception output terminal, a second filter that is connected between the common terminal and the second reception output terminal and that has a passband different from that of the first filter, and an impedance matching circuit that is disposed between the common terminal and the second filter. The impedance matching circuit includes a serial arm resonator disposed in series on a path connecting the common terminal to the second filter.