PCB SIW Front-End Module for Lightweight Tunable LTE Filtering
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Solution Overview
Problem
Existing cellular base station front-end modules, particularly for small cell and portable LTE base stations, face challenges in reducing size, weight, and cost while maintaining performance across multiple frequency bands, with conventional duplexer technologies being bulky and heavy, leading to issues like warpage during manufacturing and assembly.
Innovation Solution
The integration of substrate integrated waveguide (SIW) filters and tunable ferrite slabs on a single circuit card assembly, along with a digital analog converter and microcontroller for frequency tuning, allows for a compact, lightweight, and frequency-agile front-end module design, reducing the weight and size of the base station while maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional duplexer technologies are used, then filtering performance is achieved, but size and weight increase
Solution Approach 1:
The patent replaces conventional mechanical/cavity filter structures with substrate integrated waveguide (SIW) filters fabricated on PCB layers. This substitution of the filtering mechanism achieves the required filtering performance while dramatically reducing the weight and size of the duplexer assembly.
Solution Approach 2:
The patent changes the physical state and configuration of the filtering structure by transitioning from bulky cavity filters to planar SIW filters with specific dielectric constant and thickness parameters. This parameter change enables compact integration while maintaining filtering performance.
2Reliability
If conventional duplexer technologies are used, then filtering performance is achieved, but device size increases
Solution Approach 1:
The patent replaces conventional mechanical/cavity filter structures with substrate integrated waveguide (SIW) filters fabricated on PCB layers. This substitution of the filtering mechanism achieves the required filtering performance while dramatically reducing the weight and size of the duplexer assembly.
Solution Approach 2:
The patent transitions from three-dimensional cavity filters to two-dimensional planar SIW filter structures on PCB layers, enabling compact integration and reducing the overall device footprint while maintaining filtering performance.
3Device complexity
If fixed frequency filters are used, then simple design is achieved, but frequency band adaptability decreases
Solution Approach 1:
The patent introduces tunable elements (varactor diodes, ferrite materials, or MEMS structures) into the SIW filter design, enabling dynamic adjustment of the filtering frequency. This allows the duplexer to adapt to multiple frequency bands while maintaining a relatively simple base design structure.
Solution Approach 2:
The patent designs the SIW filter with tunable characteristics that enable it to perform multiple filtering functions across different frequency bands, making the duplexer universally applicable to various LTE bands and other wireless standards without requiring separate fixed-frequency filter assemblies.
4Volume of moving object
If PCB layers with different thicknesses are integrated, then compact integration is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent integrates multiple PCB layers with different thicknesses into a single assembled structure, combining thin component mounting layers with thicker SIW filter layers. This merging achieves compact integration while the patent addresses manufacturing precision through careful design of via holes, alignment features, and tolerance specifications.
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 solution enables a fully-integrated, lightweight, and frequency-agile LTE base station with reduced size and weight, improved electromagnetic shielding, and efficient manufacturing processes, addressing the limitations of conventional technologies by providing better isolation and tunability across multiple frequency bands.
Implementation Method 1
The at least one ferrite slab may be configured—for example, shaped, arranged, or both—to interfere with the electromagnetic field patterns of the SIW thereby rendering the SIW tunable
Implementation Method 2
The circuit card assembly may include at least one electromagnet deployed on a chassis holding the circuit card assembly. The circuit card assembly may include a means for biasing the magnetic field emitted by the at least one electromagnet to provide an orthogonal magnetic field to the ferrite slabs
Implementation Method 3
The means for biasing the magnetic field emitted by the at least one electromagnet to provide an orthogonal magnetic field to the ferrite slabs thereby varying the magnetic field applied to the SIW by the ferrite slab
Implementation Method 4
The microcontroller may be configured to control an output DC voltage of the DAC to vary a capacitance of the varactor diode, thereby tuning the SIW
Data Source
AI summary
System, apparatuses and methods are disclosed which relate to the use of substrate integrated waveguide technology in front-end modules. An example circuit card assembly for use as a cellular base station front-end is disclosed which includes at least one component printed circuit board (PCB) layer having front-end module hardware components and at least one filter PCB layer including at least one substrate integrated waveguide (SIW) filter.