Filter Multiplexer Sub-Wire Shielding for Passband Leakage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing filters with additional circuits suffer from signal leakage paths between wires, leading to inadequate attenuation outside the pass band.
Innovation Solution
A filter design incorporating a first filter circuit with a resonator electrode and an additional circuit featuring an IDT electrode group, where sub-wires are covered with a metal film shielded by an insulating layer connected to a ground terminal, reducing signal leakage paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an additional circuit is connected in parallel to the filter circuit to cancel unwanted waves, then the attenuation outside the pass band is improved, but signal leakage paths are generated between wires causing inadequate attenuation
Solution Approach 1:
A ground wire is introduced as an intermediary element between the additional circuit wire and the filter circuit wire. This ground wire acts as a mediator to provide a controlled reference potential and prevent unwanted capacitive coupling, thereby eliminating signal leakage paths while maintaining the attenuation function of the additional circuit.
Solution Approach 2:
The invention establishes equipotential regions by connecting wires to ground terminals at specific positions. By maintaining equal potential between adjacent wires through ground connections, the electric field between them is minimized, reducing capacitive coupling and signal leakage while preserving the desired attenuation characteristics.
2Area of stationary object
If wires in the additional circuit are placed close to wires in the filter circuit for compact design, then device area is reduced, but capacitance coupling increases causing signal leakage
Solution Approach 1:
Ground wires are positioned between adjacent signal-carrying wires to serve as electromagnetic shields. These intermediary ground wires are connected to ground terminals, creating equipotential barriers that block capacitive coupling between signal wires while allowing the wires to remain in close proximity for compact layout.
Solution Approach 2:
By connecting ground wires to ground terminals at multiple positions, the invention creates equipotential regions between adjacent signal wires. This equipotential configuration minimizes the electric field between signal wires, reducing capacitance coupling effects while maintaining compact spacing between circuit elements.
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
Ensures effective attenuation outside the pass band by minimizing capacitance coupling and signal leakage between wires, enhancing the filter's performance.
Implementation Method 1
At least a portion of the sub-wire includes a third metal film connected to the IDT electrode group. The third metal film is covered with a fourth metal film with an insulating layer interposed therebetween, the insulating layer being provided on the third metal film. The fourth metal film is connected to a ground terminal on the substrate.
Data Source
AI summary
A filter includes a first filter circuit and an additional circuit. The first filter circuit includes a resonator electrode and a main wire. The main wire includes first and second metal films, the second metal film being in contact with the first metal film. The additional circuit includes an IDT electrode group including IDT electrodes and a sub-wire connecting the IDT electrode group to the first filter circuit. At least a portion of the sub-wire includes a third metal film connected to the IDT electrode group. The third metal film is covered with a fourth metal film with an insulating layer interposed therebetween, the insulating layer being provided on the third metal film. The fourth metal film is connected to a ground terminal on a substrate.