Airbridge Isolation Network for Multi-Way Power Dividers
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Solution Overview
Problem
Existing power dividers and combiners for RF and microwave communications systems face challenges in achieving perfect performance for multi-way power splits beyond 2-way designs, particularly in planar circuits, due to the need for a third dimension to realize isolation resistors, leading to asymmetric designs with degraded match, isolation, and bandwidth.
Innovation Solution
A planar isolation network using a series of isolation channels with airbridges and a common resistor bus connects isolation resistors, enabling a symmetric multi-way power divider/combiner with high isolation and low insertion loss, compatible with technologies like MMIC and alumina thin film circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a 3rd dimension is used to realize isolation resistors in Wilkinson-type power dividers, then perfect isolation and match are achieved, but planar circuit implementation becomes impossible
Solution Approach 1:
The patent uses airbridges to create vertical connections that effectively add a third dimension to the planar circuit. The airbridges span across isolation resistors, allowing isolation elements to be placed in the vertical dimension while maintaining overall planar circuit layout, thus resolving the contradiction between needing 3D isolation resistors and maintaining planar manufacturability
2Ease of manufacture
If conventional planar designs remove isolation resistors to achieve planar layout, then planar symmetry is maintained, but isolation and bandwidth are degraded
Solution Approach 1:
The airbridge structure enables isolation resistors to be positioned in the vertical dimension above the planar circuit plane. This allows the circuit to maintain a planar footprint for manufacturing while incorporating 3D isolation elements that restore isolation performance and bandwidth without compromising planar symmetry
3Ease of manufacture
If asymmetric planar designs are used for multi-way power division, then planar implementation is achieved, but match, isolation, and bandwidth are degraded
Solution Approach 1:
The airbridge isolation structures enable symmetric planar layouts to be maintained while incorporating vertical isolation elements. This restores the symmetry required for optimal match and isolation performance in multi-way power dividers, eliminating the need for asymmetric designs and their associated performance degradations
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 solution provides superior performance with high isolation and low insertion loss, significantly improving upon conventional asymmetric designs by maintaining symmetry and expanding bandwidth, making it suitable for a wide range of power division ratios.
Implementation Method 1
an airbridge coupled between the common side port and the split side port and suspended over the substrate
Implementation Method 2
an isolation resistor disposed on the substrate below a respective airbridge and having a first end coupled to a respective isolation channel
Data Source
AI summary
An isolation network for multi-way power divider/combiners is provided. The isolation network provides a planar power divider/combiner according to an ideal design. Embodiments realize the isolation network using a series of isolation channels, each with an airbridge spanning over an isolation resistor and a common resistor bus connecting the isolation resistors together. In this manner, a symmetric multi-way power divider/combiner can be provided with superior performance to conventional approaches, including high isolation and low insertion loss.