SAW Filter Antenna Pad Inductor Attenuation
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Solution Overview
Problem
Conventional SAW filters and duplexers face challenges in achieving sufficient attenuation characteristics in high and ultra-high frequency bands due to design space limitations and increased material costs, while maintaining miniaturization and performance, especially with the emergence of diverse frequency communication systems like GPS and 5G.
Innovation Solution
The solution involves separating antenna pads connected to filters passing different frequency bands and selectively inserting inductors into these pads to adjust attenuation regions, allowing for improved attenuation characteristics across a wide frequency range without compromising miniaturization or increasing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional SAW filters and duplexers are used in high frequency bands, then miniaturization is achieved, but attenuation characteristics deteriorate due to design space limitation and increased coupling
Solution Approach 1:
The antenna pad is divided into first and second antenna pads that are separated from each other. The first antenna pad is connected to the first filter circuit, and the second antenna pad is connected to the second filter circuit. This segmentation allows independent optimization of each pad's characteristics, enabling improved attenuation in high frequency bands while maintaining miniaturization.
Solution Approach 2:
Inductors are selectively inserted only in specific antenna pads (first or second) depending on the required attenuation characteristics. By locally modifying only the necessary pad with an inductor, the patent achieves improved attenuation in specific frequency regions without unnecessarily increasing the overall filter size or complexity.
2Reliability
If additional inductors and capacitors are connected outside the SAW filter to secure high frequency attenuation, then attenuation characteristics improve, but device complexity and material cost increase
Solution Approach 1:
The inductor is integrated directly into the antenna pad structure of the SAW filter, merging the matching component with the filter's existing architecture. This eliminates the need for separate external matching stages, reducing overall device complexity while maintaining the ability to achieve desired attenuation characteristics in high frequency bands.
Solution Approach 2:
The antenna pad is designed to serve multiple functions: it acts as both the antenna connection point and the location for impedance matching through the integrated inductor. This multi-functionality eliminates the need for separate matching components, reducing device complexity while achieving both miniaturization and improved attenuation.
3Reliability
If inductors are inserted in antenna pads to adjust attenuation regions, then attenuation characteristics in wide frequency range improve, but manufacturing complexity increases
Solution Approach 1:
The inductor is nested within or directly integrated into the antenna pad structure during the same manufacturing process. This nesting approach allows the inductor to be formed simultaneously with the antenna pad patterns using standard semiconductor fabrication techniques, avoiding complex post-manufacturing assembly steps while enabling adjustable attenuation characteristics.
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 SAW filters and duplexers to maintain existing miniaturization characteristics while securing excellent attenuation characteristics in high and ultra-high frequency regions, with adjustable inductance values and optional shunt capacitors enhancing performance.
Implementation Method 1
at least one inductor connected in series between the common terminal and the first filter circuit or the second filter circuit
Implementation Method 2
a first filter circuit having a first frequency band as a pass band, and connected to the common terminal and the transmission terminal; a second filter circuit having a second frequency band different from the first frequency band as a pass band
Data Source
AI summary
A SAW filter is a high-frequency filter including a common terminal, a transmission terminal and a reception terminal through which high-frequency signals are inputted and outputted. The SAW filter includes: a first filter circuit having a first frequency band as a pass band, and connected to the common terminal and the transmission terminal; a second filter circuit having a second frequency band different from the first frequency band as a pass band, and connected to the common terminal and the reception terminal; an antenna connected to the common terminal; and at least one inductor connected in series between the common terminal and the first filter circuit or the second filter circuit.