PCB Diplexer Filters on Opposite Sides for High Isolation
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Solution Overview
Problem
Achieving high isolation between transmit and receive frequency bands in base station transceivers is challenging due to the close proximity of filter components in active antenna array systems, leading to coupling and reduced isolation levels.
Innovation Solution
A printed circuit board (PCB) design with filters placed on opposite sides, utilizing solder-patches for mechanical and electrical connection, and a conductive layer as a shielding ground plane to suppress crosstalk, achieving high integration and isolation through a wave guide structure adapted to the wavelength of interfering frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If filters are placed close together in active antenna array systems to achieve high integration, then device integration level is improved, but coupling between devices increases and isolation is reduced
Solution Approach 1:
The patent applies dimensionality change by moving the second filter from the same side of the PCB to the opposite side, utilizing the third dimension (depth/layering) to separate components. This spatial reconfiguration maintains close integration while achieving electromagnetic isolation through the PCB substrate barrier.
Solution Approach 2:
The PCB substrate acts as an intermediary barrier between the two filters. By placing filters on opposite sides of the PCB, the substrate material serves as a shielding medium that blocks electromagnetic coupling while allowing mechanical integration, thus resolving the crosstalk issue without sacrificing integration.
2Device complexity
If filters are placed on the same side of the PCB, then device complexity is reduced, but isolation between transmit and receive bands deteriorates
Solution Approach 1:
The invention transitions from a two-dimensional planar arrangement to a three-dimensional layered arrangement by placing filters on opposite PCB sides. This dimensional change enables isolation without increasing operational complexity, as the PCB structure inherently provides the separation barrier.
3Object-affected harmful factors
If isolation between transmit and receive bands is increased by placing filters far apart, then crosstalk is reduced, but integration level and compactness are reduced
Solution Approach 1:
Instead of increasing lateral distance between filters, the patent utilizes the vertical dimension by placing filters on opposite PCB sides. This approach achieves electromagnetic isolation equivalent to large separations while maintaining compact PCB footprint, effectively trading lateral space for vertical layering.
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
The PCB design effectively suppresses crosstalk and achieves isolation levels of over 70, 80, 90, or 100 dB, maintaining high integration while minimizing signal leakage between the transmit and receive bands.
Implementation Method 1
a conductive layer as a shielding ground plane to suppress crosstalk
Implementation Method 2
a wave guide structure adapted to the wavelength of interfering frequencies
Data Source
AI summary
A printed circuit board 100 for forming a diplexer circuit 200 comprising a first connector 110 for connecting a first filter 112 and second connector 120 for connecting a second filter 122, wherein the first connector 110 and the second connector 120 are located on opposite sides of the printed circuit board 100.