Nested RF Filter Layout for Smaller Duplexer Modules
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Solution Overview
Problem
Current radio-frequency devices face challenges in reducing the footprint of filter modules while maintaining functionality, as up to 70% of the substrate area is occupied by duplexers, necessitating a reduction in duplexer footprint without increasing costs or compromising manufacturing infrastructure.
Innovation Solution
The implementation of nested filter configurations, where a second filter device is positioned within the space defined by the underside of a first filter device and support structures, including metal and solder structures, to achieve a reduced footprint without compromising functionality, and the use of a mold structure to encapsulate the filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional filter module layout is used, then functionality is maintained, but surface area occupation is high (up to 70% of substrate area)
Solution Approach 1:
The patent implements a nested filter configuration where a first filter device and a second filter device are positioned in a nested arrangement. The second filter device is mounted on the substrate such that its support structures are between the second filter device and the mounting surface, while the first filter device is positioned within the space defined by the underside of the second filter device and its support structures. This nesting approach reduces the overall surface area occupation while maintaining both filter functionalities.
Solution Approach 2:
The patent transitions from a traditional planar layout to a three-dimensional nested configuration. By utilizing vertical space and positioning filter devices at different heights and orientations, the design achieves compact integration. The first filter device is positioned in the space under the second filter device's support structures, effectively using the third dimension (height/depth) to reduce footprint area.
2Area of stationary object
If nested filter configuration is implemented, then surface mount area is reduced by approximately 30%, but structural stability may be compromised
Solution Approach 1:
The patent incorporates support structures for the second filter device that are positioned between the second filter device and the mounting surface. These support structures provide structural reinforcement and prevent collapse of the nested configuration. The support structures act as a cushioning element that maintains structural integrity while enabling the compact nested arrangement.
Solution Approach 2:
The patent uses composite support structures that combine multiple materials with different properties. The support structures for the second filter device include both metal structures and solder structures, where the metal structure has a higher melting point than the solder structure. This composite approach provides both mechanical strength and thermal management, ensuring structural stability in the nested configuration.
3Reliability
If metal structure with higher melting point is used in support structures, then structural integrity is maintained during solder reflow, but manufacturing complexity increases
Solution Approach 1:
The patent specifies that the metal structure in the support structures has a melting point higher than that of the solder structure. This parameter change (selecting metal with higher melting point) ensures that the support structures maintain their structural integrity during the solder reflow process, preventing collapse of the nested filter configuration while allowing standard soldering manufacturing processes to be used.
Data Source
AI summary
In some embodiments, nested filters can be implemented as a radio-frequency device that includes a substrate, and first and second filter devices mounted on the substrate with respective support structures, such that at least a portion of the second filter device is positioned in a space defined by an underside of the first filter device and the support structures for the first filter device. Such a radio-frequency device can be, for example, a packaged module for use in an electronic device such as a wireless device.