FBAR Bandpass Filter Duplexer Integration
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Solution Overview
Problem
Conventional duplexers for mobile communication devices using SAW filters face challenges in miniaturization and cost due to increased size and high manufacturing costs, particularly when integrating transmitting and receiving filters with inductors and capacitors, which restricts the development of high-performance, small-sized devices.
Innovation Solution
The integration of FBAR band pass filters with inductors on a single substrate using a MEMS technique, where FBARs with piezoelectric layers and electrodes are formed on a semiconductor substrate, allowing for a compact design and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SAW filters are used in duplexers, then the duplexer can separate transmitting and receiving frequencies, but the size of the duplexer is essentially increased
Solution Approach 1:
The patent integrates the inductor and capacitor directly into the FBAR filter structure, merging previously separate components into a single integrated device. This reduces the overall number of discrete components and their associated packaging requirements, thereby reducing the duplexer size while maintaining frequency separation capability
Solution Approach 2:
The FBAR filter structure is designed to perform multiple functions simultaneously - acting as both the filtering element and incorporating the inductor and capacitor functions within its structure. This multi-functionality eliminates the need for separate discrete components, reducing the overall duplexer footprint
2Reliability
If SAW band pass filter is utilized with ceramic package, then the filter can be packaged, but the manufacturing cost is increased
Solution Approach 1:
The inductor, capacitor, and filter are merged into a single integrated FBAR device, eliminating the need for separate ceramic packaging. This integration reduces manufacturing steps and material costs while maintaining the protective packaging function
Solution Approach 2:
The patent extracts the inductor and capacitor from their traditional separate packaged forms and integrates them directly into the FBAR filter structure. This eliminates the need for expensive ceramic packaging while maintaining the necessary protective and functional requirements
3Reliability
If impedance matching network is packaged with SAW filter, then the network is protected, but it is difficult to manufacture and cost is increased
Solution Approach 1:
The impedance matching network components (inductor and capacitor) are merged directly into the FBAR filter structure, eliminating the need for separate packaging. This integration simplifies the manufacturing process by reducing the number of discrete components and assembly steps while maintaining protective functionality
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 approach enables the creation of a compact duplexer with low insertion loss and low power consumption, significantly reducing the size and manufacturing costs while enhancing frequency extraction and noise removal capabilities, thus supporting the miniaturization and cost-effectiveness of mobile communication devices.
Implementation Method 1
The FBAR is one to use a principle that if the piezoelectric material applies electrical energy to both electrodes disposed between, en electric field being timely varied within a piezoelectric layer is maintained and a bulk acoustic wave is generated according to the electric field
Implementation Method 2
a bulk acoustic wave is generated according to the electric field
Data Source
AI summary
A duplexer includes an FBAR band pass filter that can be easily embodied in single chip. A method for manufacturing the same includes the steps of forming a plurality of recesses in a substrate, forming an insulation layer on the substrate, and forming a plurality of filling-up layers that fill the recesses. The method also includes the step of forming a transmitting bandpass filter and forming a receiving bandpass filter on an upper side of the membrane, with each bandpass filter including at least two film bulk acoustic resonators (FBARs). In addition, the method includes the step of forming a circuit that connects the bandpass filters to an antenna terminal, with this circuit including at least one inductor and capacitor. The method also includes a step of removing the filling-up layers from the recesses in the substrate.