SAW Filter Ground Terminal Separation for Sharper Skirt Response
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Solution Overview
Problem
Conventional SAW filters face challenges in achieving effective attenuation and maintaining skirt characteristics when reduced in size, leading to deteriorated performance on high frequency transmission and low frequency reception stages.
Innovation Solution
The SAW filter design separates ground terminals connected to IDT electrodes, incorporating serial and parallel resonators and reflectors to enhance attenuation effects and improve skirt characteristics, while maintaining an equivalent pass band characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of SAW filter is reduced, then miniaturization is achieved, but attenuation effect deteriorates
Solution Approach 1:
The ground terminals are segmented into multiple separate terminals (first ground terminal and second ground terminal) instead of using a single common ground terminal. This segmentation allows independent control of ground connections for different IDT electrode groups, enabling improved attenuation performance in a compact filter structure.
2Volume of moving object
If the size of SAW filter is reduced, then miniaturization is achieved, but skirt characteristic deteriorates
Solution Approach 1:
The ground terminals are segmented into multiple separate terminals (first ground terminal and second ground terminal) instead of using a single common ground terminal. This segmentation allows independent control of ground connections for different IDT electrode groups, enabling improved skirt characteristics in a compact filter structure.
3Loss of energy
If ground terminals are separated, then attenuation effect improves, but device complexity increases
Solution Approach 1:
The ground terminals are segmented into multiple separate terminals (first ground terminal and second ground terminal) connected to different IDT electrode groups. This segmentation improves attenuation effect while the complexity increase is managed through systematic connection patterns.
Solution Approach 2:
The separated ground terminal configuration serves multiple functions simultaneously: it provides improved attenuation effect, maintains or improves skirt characteristics, and enables independent impedance control for different signal paths, making the structure multi-functional despite increased complexity.
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 separation of ground terminals in the SAW filter design improves attenuation and skirt characteristics on both high frequency transmission and low frequency reception stages, achieving an equivalent pass band characteristic and simplifying the process by reducing the number of bridge electrodes.
Implementation Method 1
a converter of a comb pattern, that is, a metal electrode, is formed in a substrate having a piezo-electric property. When an electric field is applied to the substrate, a surface of the substrate is temporarily twisted. A SAW is generated by such an action.
Implementation Method 2
The SAW generated as described above delays an input electrical signal or transmits only a specific frequency signal because it is slower than electromagnetic waves.
Implementation Method 3
The IDT electrode functions to apply an electrical signal to a piezo-electric body and to convert a SAW generated from the piezo-electric body into an electrical signal.
Data Source
AI summary
A SAW filter in which a plurality of IDT electrodes is disposed in the propagation direction of a SAW and ground terminals are separated. The present invention has an advantage in that the attenuation effect of the SAW filter is improved. Furthermore, a skirt characteristic on the high frequency side of a transmission stage and a skirt characteristic on the low frequency side of a reception stage can be improved. Furthermore, an equivalent pass band characteristic can be achieved and a skirt characteristic on the high frequency side and a skirt characteristic on the low frequency side can be improved. Furthermore, the number of bridge electrodes can be reduced and thus a process can be simplified because ground terminals are separated.