IDT Filter Circuit Layout for Attenuation and Isolation
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Solution Overview
Problem
Existing filter and multiplexer configurations face challenges in size reduction and complexity due to complicated wiring, particularly with ground connections, which affect attenuation and isolation characteristics.
Innovation Solution
The use of multiple-stage IDT electrode groups with common connections simplifies ground wiring and enhances phase adjustment, allowing for improved attenuation characteristics and size reduction by eliminating the need for ground connections between certain IDT electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each IDT electrode is connected to ground individually, then attenuation characteristics are improved, but wiring complexity increases and device size increases
Solution Approach 1:
The patent combines multiple ground connections into a single common ground connection. Specifically, the second IDT electrode and the fourth IDT electrode are both connected to ground through a shared ground connection rather than individual ground connections, thereby reducing wiring complexity while maintaining the necessary reference potential for signal cancellation functionality
Solution Approach 2:
The common ground connection serves multiple functions simultaneously: it provides the reference potential for both the second IDT electrode and the fourth IDT electrode, enables signal cancellation for multiple frequency bands, and reduces the overall wiring structure. This multi-functional approach resolves the contradiction by achieving attenuation characteristics without proportional increases in wiring complexity
2Reliability
If each IDT electrode is connected to ground individually, then attenuation characteristics are improved, but device area increases
Solution Approach 1:
The patent merges multiple ground connections into a single common ground connection point. By having the second IDT electrode and fourth IDT electrode share a common ground connection, the physical area required for ground wiring is significantly reduced compared to individual ground connections for each electrode
3Measurement precision
If multiple-stage IDT electrode groups are used, then phase adjustment precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the cancellation circuit into multiple-stage IDT electrode groups (first, second, third, and fourth IDT electrodes arranged in stages). Each stage can be independently adjusted to achieve precise phase control for different frequency bands. The segmentation allows progressive refinement of phase adjustment while sharing common ground connections to limit complexity growth
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 achieves better attenuation characteristics and isolation while reducing the area required for ground wiring, enabling more accurate phase adjustments and smaller filter and multiplexer designs.
Implementation Method 1
IDT (Inter Digital Transducer) electrode groups which generate acoustic waves
Implementation Method 2
acoustic wave propagation direction
Data Source
AI summary
A filter includes an additional circuit including first and second IDT electrode groups connected in multiple stages between first and second input/output terminals, the first IDT electrode group includes first and second IDT electrodes side by side in a propagation direction of an acoustic wave, and the second IDT electrode group includes third and fourth IDT electrodes side by side in the propagation direction. One end of each of the first and second IDT electrodes is respectively connected to the first and second input/output terminals. Other ends of the first and second IDT electrodes are connected in common and to a ground. One ends of the third and fourth IDT electrodes are connected in common. Other ends of the third and fourth IDT electrodes are connected in common. The additional circuit is connected in parallel with at least a portion of a filter circuit.