Acoustic Wave Filter Electrode Layout for Steep Passband Edges

The patent applies local quality by using different electrode finger structures (floating withdrawal electrodes vs. conventional connected electrodes) in different regions of the IDT electrode. The floating withdrawal electrodes are strategically placed at specific positions to improve steepness only where needed, while other regions maintain conventional structures to preserve low loss characteristics, thus achieving local optimization of both steepness and loss performance.

The patent changes the electrical connection parameter of specific electrode fingers from connected to floating (unconnected), which fundamentally alters the resonant characteristics. This parameter change allows selective modification of resonant band width and Q factors for specific electrodes, enabling improvement of steepness through controlled parameter variation without uniformly degrading pass band loss across all electrodes.

The patent implements local quality by applying floating withdrawal electrode structures only to specific IDT electrodes (first through fourth IDT electrodes) while maintaining conventional structures in other electrodes. This localized application allows precise control over which resonant characteristics are modified, enabling independent optimization of steepness and resonant band width/Q factor stability for different electrode pairs.

The patent segments the IDT electrode structure into multiple independent electrode pairs (first, second, third, fourth IDT electrodes), each with potentially different connection configurations. This segmentation allows each electrode pair to be independently optimized with appropriate floating or conventional structures, providing fine-grained control over the overall filter characteristics including steepness and resonant stability.