Adjacent RF Filter Layout for Transmission-Receive Isolation
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Solution Overview
Problem
In high-frequency circuits processing RF signals across multiple frequency bands, increased integration leads to signal coupling between transmission and reception circuits, deteriorating isolation and causing undesirable signal characteristics.
Innovation Solution
A filter device configuration where adjacent filters have forbidden regions along their sides with no wires extending, preventing signal coupling by ensuring wires intersect with sides rather than aligning, and allowing separate filter elements to enhance isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the degree of integration is increased in high-frequency circuits, then circuit density and compactness are improved, but signal coupling between transmission and reception circuits increases, deteriorating isolation
Solution Approach 1:
A ground electrode is introduced as an intermediary element between adjacent filters to provide electromagnetic shielding. The ground electrode acts as a mediator that blocks parasitic capacitance coupling between signal lines of adjacent filters, thereby reducing signal coupling while maintaining high integration density.
Solution Approach 2:
The harmful parasitic capacitance coupling is extracted and eliminated by introducing a ground electrode that physically separates the signal paths. The ground electrode removes the harmful electromagnetic interaction between adjacent filters by providing a reference potential barrier.
2Area of stationary object
If filters are arranged adjacently to achieve compact layout, then device area is reduced, but isolation between filters deteriorates due to signal coupling
Solution Approach 1:
A ground electrode is positioned between adjacent filters to serve as an electromagnetic shield. This intermediary structure blocks the parasitic capacitance coupling between the signal lines of adjacent filters, maintaining signal isolation while enabling compact adjacent arrangement of filters.
Solution Approach 2:
The ground electrode is selectively positioned only in the critical regions where parasitic capacitance coupling occurs between adjacent filters. This local shielding approach provides effective isolation where needed while maintaining overall device compactness and not unnecessarily increasing total device area.
3Ease of operation
If wires extend along sides in forbidden regions, then connectivity is improved, but coupling between adjacent filters increases through the wiring
Solution Approach 1:
The ground electrode acts as an intermediary barrier that prevents signal coupling through wires that must pass near adjacent filters. Even when wiring connectivity is maintained, the ground electrode blocks the harmful electromagnetic coupling that would otherwise occur through the forbidden region.
Data Source
AI summary
A transmission filter is arranged in a first filter region and has one or more acoustic wave resonators, a plurality of terminal electrodes, and a plurality of wires. A reception filter is arranged in a second filter region and has one or more acoustic wave resonators, a plurality of terminal electrodes, and a plurality of wires. The first filter region and the second filter region are arranged adjacently to each other and have at least sides constituting a pair and opposing to each other. At least either one of the first filter region and the second filter region has no wire extending along one side in a forbidden region that is defined by a width including a terminal electrode nearest to the one side, along the one side and over the one side opposing to the other filter region.