Composite Multiplexer Isolation via LC Interposers
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Solution Overview
Problem
In 5G communication systems, existing LC filters exhibit insufficient steepness and isolation characteristics due to increased residual inductance and stray capacitance at high frequencies, making them unsuitable for multiplexers in frequency bands of 3 GHz to 6 GHz.
Innovation Solution
A composite multiplexer design incorporating band pass filter circuits with LC circuits and 90-degree delay circuits, including acoustic wave filters, to enhance filter steepness and isolation characteristics by interposing LC circuits between filter ends and connecting duplexer components in a manner that aligns signal phases and reduces interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If LC filters are used in frequency bands of 3 GHz to 6 GHz, then the device can operate in high-frequency bands, but the isolation characteristic between filters becomes insufficient due to increased residual inductance and stray capacitance
Solution Approach 1:
A ground electrode is introduced as an intermediary element between the series electrode and the end electrode of the acoustic wave filter. This ground electrode acts as a mediator to reduce the influence of residual inductance and stray capacitance, thereby improving isolation characteristics between filters operating in high-frequency bands (3 GHz to 6 GHz) without compromising the frequency band capability
Solution Approach 2:
The electrode structure is segmented into multiple distinct components: series electrode, ground electrode, and end electrode. By dividing the原本 continuous electrode path into separate segments with the ground electrode in between, the patent reduces parasitic effects and improves isolation characteristics while maintaining high-frequency operation capability
2Speed
If the line widths of electrode fingers are reduced to achieve higher frequencies in acoustic wave filters, then the frequency can be increased, but production variations increase and electric power handling capability decreases
Solution Approach 1:
Instead of increasing frequency by reducing the dimensions (line widths) of electrode fingers in the planar dimension, the patent introduces a ground electrode that creates a new dimensional approach to frequency control through acoustic wave mode management. This allows higher frequencies to be achieved without compromising manufacturing precision or power handling capability
3Device complexity
If a single multiplexer structure is used, then the device complexity is low, but the isolation characteristic between filters is insufficient at high frequencies
Solution Approach 1:
A ground electrode is introduced as an intermediary element between the series electrode and the end electrode of the acoustic wave filter. This ground electrode acts as a mediator to reduce the influence of residual inductance and stray capacitance, thereby improving isolation characteristics between filters operating in high-frequency bands (3 GHz to 6 GHz) without compromising the frequency band capability
Solution Approach 2:
The electrode structure is segmented into multiple distinct components: series electrode, ground electrode, and end electrode. By dividing the原本 continuous electrode path into separate segments with the ground electrode in between, the patent reduces parasitic effects and improves isolation characteristics while maintaining high-frequency operation capability
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
The solution effectively improves isolation and filter steepness, maintaining performance across high-frequency bands without reducing electrode line widths or increasing production variability, thus addressing the limitations of existing LC filters.
Implementation Method 1
an acoustic wave filter that uses an S0 mode of plate waves, the frequency is able to be increased easily. For example, in an acoustic wave filter described in WO 2017/068827, an acoustic multilayer film and a piezoelectric film are stacked on a support substrate. In the S0 mode of plate waves that propagate along the piezoelectric film, the acoustic velocity is as high as about 6000 m/sec.
Implementation Method 2
The plurality of first LC circuits may define attenuation poles defining pass bands of the band pass filter circuits. In this case, the steepness of filter characteristics of the first multiplexer is able to be increased effectively.
Data Source
AI summary
A composite multiplexer includes a first multiplexer, a second multiplexer, and a second LC circuit. The first multiplexer includes first band pass filter circuits and first LC circuits connected to end portions of the first band pass filter circuits that are opposite to a first terminal, respectively. The second multiplexer includes second band pass filter circuits. The second LC circuit is connected between the first terminal and the second multiplexer.