Electrical Balance Duplexer With Tunable Isolation Across FDD Bands
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Solution Overview
Problem
Current front-end modules in mobile communication devices face challenges in achieving sufficient signal isolation between transmit and receive frequencies due to the frequency-dependent impedance of commercial antennas, limiting the bandwidth for effective isolation in frequency-division duplexing systems, which results in increased complexity and cost with the use of fixed-frequency filters.
Innovation Solution
The implementation of an electrical balance duplexer circuit with a hybrid transformer and tunable impedance circuit, utilizing filters at either the transmit or receive port to achieve isolation, allowing for reduced complexity in the tuneable impedance circuit design and improved power flow by compensating for reduced isolation with attenuation, thereby simplifying the design and enhancing performance across multiple frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed-frequency filters are used to isolate transmit and receive signals, then isolation performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple filter functions into a single reconfigurable filter that can dynamically adjust its characteristics. Instead of using separate fixed-frequency filters for each band, the invention employs one filter structure that can be reconfigured to serve multiple bands through electronic control, thereby reducing overall device complexity while maintaining isolation performance.
Solution Approach 2:
The patent introduces dynamic reconfigurability to the filter system. The filter's resonant frequency and impedance characteristics can be dynamically adjusted based on the operating band requirements. This allows a single filter to adaptively provide the necessary isolation for different frequency bands, replacing multiple static filters and reducing system complexity.
2Reliability
If fixed-frequency filters are used for each band, then signal isolation is improved, but the device becomes bulky
Solution Approach 1:
The patent designs a universal reconfigurable filter that can perform the isolation function for multiple frequency bands. This single multi-functional filter replaces what would traditionally require multiple band-specific filters, significantly reducing the volume occupied by filtering components in the front-end module while maintaining the necessary isolation performance across all bands.
Solution Approach 2:
The reconfigurable filter structure allows for a more compact design where the same physical component serves multiple functions. The filter can be nested within a single integrated circuit or module structure, allowing it to provide isolation for multiple bands without requiring separate discrete filter components for each band, thereby reducing overall FEM volume.
3Device complexity
If EBD circuit is used to support multiple bands, then device complexity is reduced, but isolation bandwidth is limited due to antenna impedance frequency dependency
Solution Approach 1:
The patent employs a reconfigurable filter with dynamically adjustable resonant frequency and impedance characteristics. This allows the filter to adapt to the frequency-dependent antenna impedance across different bands, maintaining effective isolation over a wider bandwidth. The dynamic adjustment capability enables the filter to track and compensate for impedance variations that would otherwise limit isolation performance.
Solution Approach 2:
The patent changes the operational parameters of the reconfigurable filter based on the active frequency band. By adjusting parameters such as resonant frequency, quality factor, and impedance matching characteristics, the filter can maintain optimal isolation performance across multiple bands despite the antenna's frequency-dependent impedance. This parameter adaptation overcomes the bandwidth limitations of fixed-parameter EBD circuits.
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 effective isolation between transmit and receive signals across multiple frequency bands, reducing signal losses and improving power flow, while simplifying the design of the tuneable impedance circuit and reducing the complexity of the balance network, thus addressing the limitations of existing technologies.
Implementation Method 1
They operate based on signal cancellation using a hybrid transformer, essentially by 'balancing' an antenna Z ANT and a tuneable impedance circuit, the so-called balance network or Z BAL.
Implementation Method 2
electrical balance duplexers, EBDs
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The present disclosure relates to a front-end module for a telecommunication device with an EBD circuit (1) comprising a hybrid transformer (2) for coupling via a transmit port (21) to the telecommunication device transmitting a first frequency transmit signal, to an antenna (4), via a receive port (23) to the telecommunication device receiving a second frequency receive signal, and to a tuneable impedance circuit (6). In a first configuration the EBD circuit (1) is configured to isolate the transmit port (21) from the receive port (23) at the first frequency, and the FEM comprises a first filter (7) at the transmit port (21) for attenuating the transmit signal with a predetermined amount at the second frequency. In a second configuration the EBD circuit (1) is configured to isolate the transmit port (21) from the receive port (23) at the second frequency, and the FEM comprises a second filter (8) at the receive port (23) for attenuating the receive signal a predetermined amount at the first frequency.