Acoustic Wave Multiplexer Resonance Circuit for Impedance Matching
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Solution Overview
Problem
The existing multiplexers with acoustic wave filters face an imbalance in impedance due to the addition of inductance elements, leading to increased insertion loss as the impedance in the second pass band shifts away from the reference impedance, causing a matching loss.
Innovation Solution
A multiplexer design incorporating a common terminal, a first inductance element, a first acoustic wave filter, a second acoustic wave filter with a higher frequency pass band, a second inductance element connected between ground and the path linking the filters, and a capacitance element between the path and ground, where the resonant frequency of the LC parallel resonance circuit is positioned between the first and second pass bands, thereby aligning impedances with the reference impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inductance element is added to the second acoustic wave filter to achieve impedance matching, then the impedance in the second pass band can be adjusted, but the impedance shifts away from the reference impedance when the capacitance component is large, causing matching loss and increased insertion loss
Solution Approach 1:
A resonance circuit is introduced as an intermediary element connected between the second acoustic wave filter and ground. This resonance circuit, comprising a second inductance element and a capacitance element, mediates the impedance transformation to achieve accurate complex conjugate matching between the two pass bands without causing the impedance to shift away from the reference impedance
Solution Approach 2:
The impedance characteristics are optimized by carefully selecting the inductance and capacitance values of the resonance circuit elements. The resonant frequency of the resonance circuit is set to a specific value to control the impedance transformation, enabling accurate impedance matching while minimizing insertion loss
2Ease of operation
If an inductance element is added to adjust impedance, then some impedance control is achieved, but an imbalance is caused between the inductive impedance in the second pass band and the capacitive impedance in the first pass band, preventing accurate impedance matching
Solution Approach 1:
The resonance circuit serves as an intermediary that transforms the impedance in a controlled manner. By positioning the resonant frequency appropriately and selecting suitable component values, the circuit achieves balanced complex conjugate impedance relationships between different pass bands, enabling accurate overall impedance matching
Solution Approach 2:
The resonance circuit introduces dynamic impedance transformation characteristics that vary with frequency. This dynamic behavior allows the circuit to provide different impedance transformations at different frequencies, achieving accurate matching across multiple pass bands simultaneously
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 insertion loss by accurately matching the impedance in the pass bands of the multiplexers, ensuring efficient signal transmission across the frequency range.
Implementation Method 1
a resonant frequency of a resonance circuit including the second inductance element and the capacitance element is located between the first pass band and the second pass band
Data Source
AI summary
A multiplexer includes a common terminal, an inductor including a first end connected to the common terminal and a second end, a filter connected to the second end and having a first pass band, a filter connected to the common terminal and having a second pass band located on a higher frequency side relative to the first pass band, an inductor connected between a ground and a path that links the second end to the filter, and a capacitor connected between the path and the ground. A resonant frequency of an LC parallel resonance circuit including the inductor and the capacitor is located between the first pass band and the second pass band.