Vertical Switched Filter Bank PCB Stacking for RF Signal Isolation
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Solution Overview
Problem
Microwave and RF circuits face challenges due to large distances between neighboring components and transmission lines, which affect the size of circuit boards and compromise signal isolation.
Innovation Solution
The implementation of a microwave device with a printed circuit board (PCB) that includes through-holes coated with conductive material, where microwave components are mounted within these holes, and a conductive cover is used to form shielding cavities, along with stacked PCBs and flexible PCBs to enhance signal isolation and reduce size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large distances are maintained between neighboring components and transmission lines, then signal isolation is improved, but the size of the circuit board increases
Solution Approach 1:
The patent transitions from a planar two-dimensional layout to a three-dimensional stacked configuration. Multiple PCB layers are vertically stacked with components distributed across different height levels, allowing signal isolation to be achieved through vertical separation rather than horizontal distancing. This dimensional change enables compact footprint while maintaining isolation through the third dimension (height/z-axis separation).
Solution Approach 2:
The circuit board is segmented into multiple stacked PCB layers, each potentially containing different components and signal paths. This segmentation allows independent optimization of each layer for signal isolation and enables vertical stacking to achieve the required isolation distances without increasing the overall planar footprint of the device.
2Reliability
If conventional PCB layouts are used with adequate signal isolation distances, then signal fidelity is maintained, but the device profile and size increase
Solution Approach 1:
The patent uses vertical stacking of multiple PCB layers to achieve signal isolation in the z-dimension (height) rather than requiring large horizontal distances. This allows the device to maintain a low profile in the planar dimensions while achieving adequate isolation through vertical separation between signal paths on different layers.
Solution Approach 2:
Multiple PCB layers are nested vertically one above another, with each layer containing components and transmission lines. This nesting arrangement allows compact integration of multiple signal paths while maintaining isolation through the vertical stacking configuration, thereby reducing the overall device profile.
3Device complexity
If microwave components are mounted on a single PCB layer, then device complexity is reduced, but signal isolation between components is compromised
Solution Approach 1:
The patent segments the component placement across multiple PCB layers rather than concentrating all components on a single layer. This segmentation distributes microwave components vertically through the stack, allowing signal isolation to be achieved through vertical separation while maintaining relatively simple individual layer designs.
Solution Approach 2:
Instead of achieving component isolation through horizontal spacing on a single layer (2D arrangement), the patent utilizes the vertical dimension by distributing components across multiple stacked PCB layers. This 3D arrangement provides natural signal isolation through layer separation while keeping each individual layer relatively simple in design.
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 maintains signal isolation and high fidelity while reducing the size of microwave devices, enabling low-profile designs suitable for thin-film manufacturing processes.
Implementation Method 1
A conductive cover is mounted on the PCB such that the cover is in electrical contact with the ground plane of the substrate through the conductive material, forming shielding cavities around the components
Data Source
AI summary
A microwave or radio frequency (RF) device includes stacked printed circuit boards (PCBs) mounted on a flexible PCB having at least one ground plane and a signal terminal. Each of the stacked PCBs includes through-holes the sidewalls of which are coated with a conductive material. Microwave components are mounted on the flexible PCB within the through-holes, such that signal terminals of the components bond to signal terminals of respective through-holes. A conductive cover is mounted on the PCBs such that the cover is in electrical contact with the ground plane of the flexible PCB through the conductive material, forming shielding cavities around the components. The flexible PCB is folded such that the cover of one PCB faces the cover of the second PCB. The flexible PCB includes striplines or microstrips that carry RF or microwave signals to the signal terminals.