Hybrid Transformer Duplexer for Multi-Band RF Isolation
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Solution Overview
Problem
Conventional duplexers for wireless communication systems require separate components for each radio frequency band and transmission technology, leading to increased size, cost, and complexity due to their reliance on frequency-selective filters and special materials that cannot be integrated with silicon-based technology, necessitating off-chip fabrication and resulting in higher Bill of Materials and printed circuit board area.
Innovation Solution
The integration of a hybrid transformer-based duplexer that uses electrical balance for isolation, allowing a single duplexer to operate across multiple frequency bands and modes by employing a hybrid transformer with two coils and a balancing impedance, which can be fabricated using silicon-based technology, reducing the need for multiple power amplifiers and low noise amplifiers and minimizing PCB routing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate duplexers are used for each radio frequency band and transmission technology, then the device can operate on multiple RF bands with multiple transmission technologies, but the size, cost, and complexity of the device increase
Solution Approach 1:
The patent combines multiple frequency-selective filters (first filter for first RF band, second filter for second RF band) and multiple duplexers into a single integrated duplexer structure. This merging eliminates the need for separate discrete duplexers for each RF band, thereby reducing device size, cost, and complexity while maintaining multi-band operation capability
Solution Approach 2:
The integrated duplexer is designed to perform multiple functions simultaneously: it provides frequency selection for multiple RF bands (first and second bands), supports multiple transmission technologies, and enables full-duplex communication across different bands all within a single device structure, making it a universal solution for multi-band/multi-mode operation
2Reliability
If frequency-selective filters and special materials are used in conventional duplexers, then the device can provide effective frequency separation, but the materials cannot be integrated with silicon-based technology requiring off-chip fabrication
Solution Approach 1:
The patent implements frequency separation using electronic switching between different filter circuits rather than relying on special materials with fixed frequency characteristics. By changing the operational parameters (switching between first and second frequency-selective filters electronically), the system achieves frequency separation that is compatible with standard silicon-based integrated circuit fabrication processes
Solution Approach 2:
The patent replaces the mechanical/material-based frequency selection approach (using special materials that cannot be integrated) with an electronic control system that switches between different filter circuits. This substitution enables the frequency separation function to be implemented through electronic means compatible with silicon-based technology
3Reliability
If multiple separate duplexers are used, then each duplexer can be optimized for its specific band, but the Bill of Materials and printed circuit board area increase
Solution Approach 1:
The patent merges multiple band-specific filter circuits into a single integrated duplexer structure where the first frequency-selective filter and second frequency-selective filter coexist within the same device. This consolidation maintains band-specific optimization while dramatically reducing the printed circuit board area compared to using separate discrete duplexers
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 compact, cost-effective, and multi-band/multi-mode wireless device with reduced size and complexity by providing effective isolation between transmit and receive signals using electrical balance, allowing full-duplex communication over non-overlapping frequency bands without the need for separate duplexers for each band.
Implementation Method 1
a hybrid transformer with two coils
Implementation Method 2
uses electrical balance for isolation
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
An integrated duplexer based on electrical balance is described. The duplexer module includes a hybrid transformer. The hybrid transformer includes a primary coil and a secondary coil. The primary coil is coupled between an output of a power amplifier and an antenna. The secondary coil is coupled between an input of a low noise amplifier and ground. The duplexer also includes a balancing impedance that is coupled between the primary coil and the secondary coil.