Hybrid Transformer Duplexer for Low-Loss TX/RX Isolation
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Solution Overview
Problem
Modern radio front-end architectures for 3G and 4G user equipment require multiple duplexers, leading to increased financial costs and circuit board area, and existing hybrid transformer duplexer solutions suffer from significant energy inefficiency and the need for adaptive tuning due to dynamic antenna voltage standing wave ratio changes.
Innovation Solution
A hybrid transformer duplexer apparatus with a step-down transformer and autotransformer configuration that balances dual antenna ports, utilizing surface acoustical wave filters and metamaterial elements to minimize insertion loss and adapt to changing VSWR conditions, while reducing the number of resonators needed for filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hybrid transformer with balanced resistor RBAL is used to achieve electrical isolation between TX and RX ports, then isolation is improved, but insertion loss increases by at least -3 dB due to energy dissipation in RBAL
Solution Approach 1:
The patent removes the balanced resistor RBAL from the hybrid transformer circuit entirely. By extracting this energy-dissipating component, the invention eliminates the inherent -3 dB insertion loss while maintaining electrical isolation between TX and RX ports through the autotransformer configuration alone.
Solution Approach 2:
Instead of using a resistor to achieve isolation (dissipative approach), the patent inverts the approach by using a lossless autotransformer configuration that provides isolation through magnetic coupling and impedance transformation. The step-down transformer with 1:2 turns ratio creates the isolation effect without energy dissipation.
2Adaptability or versatility
If multiple duplexers are used for 3G and 4G radio bands, then frequency coverage and adaptability are improved, but circuit board area and manufacturing cost increase
Solution Approach 1:
The patent creates a universal duplexer design that can operate across multiple RF bands (including 3G and 4G frequencies) using a single hybrid transformer apparatus. The autotransformer configuration with tunable resonators provides multi-band functionality, eliminating the need for separate duplexers for different frequency ranges and reducing circuit board area.
Solution Approach 2:
The invention merges multiple duplexer functions into a single integrated hybrid transformer structure. By combining the TX port, RX port, and multiple antenna ports into one apparatus with shared resonators and transformers, the patent reduces the total component count and circuit board space required compared to using separate duplexers for each band.
3Reliability
If RBAL is dynamically tuned to match antenna VSWR changes, then isolation performance is maintained, but device complexity increases due to need for adaptive tuning circuits
Solution Approach 1:
The patent eliminates the need for external adaptive tuning circuits by making the hybrid transformer self-adjusting. The autotransformer configuration inherently adapts to VSWR changes through its magnetic coupling characteristics, and the resonators automatically track frequency variations, providing self-service isolation maintenance without additional control circuitry.
Solution Approach 2:
The invention introduces dynamic tuning capability through voltage-controlled resonators that can adjust their resonant frequencies in real-time. This dynamic adjustment allows the duplexer to maintain optimal isolation performance across varying VSWR conditions and frequency bands without requiring complex external tuning circuits, as the system adapts automatically.
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 achieves high isolation between transmit and receive signals with reduced insertion loss and adaptive tuning capabilities, minimizing the need for expensive adaptive circuits and optimizing the number of resonators required for filtering, thereby reducing costs and improving efficiency.
Implementation Method 1
an autotransformer having a first port, a second port and a tap coupled to a first antenna port. A step-down transformer has a primary winding with a first terminal coupled to the first port of the autotransformer and a second terminal coupled to the second port of the autotransformer
Implementation Method 2
utilizing surface acoustical wave filters and metamaterial elements to minimize insertion loss and adapt to changing VSWR conditions
Data Source
AI summary
The present disclosure relates to a hybrid transformer duplexer apparatus. The hybrid transformer duplexer apparatus includes an autotransformer having a first port, a second port and a tap coupled to a first antenna port. A step-down transformer has a primary winding with a first terminal coupled to the first port of the autotransformer and a second terminal coupled to the second port of the autotransformer, and a secondary winding having a third terminal coupled to a second antenna port and a fourth terminal coupled to a common node.