EBD Front-End Module With Tunable Impedance for Multi-Band Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current front-end modules in mobile communication devices face challenges in achieving sufficient signal isolation across multiple frequency bands due to the frequency-dependent impedance of commercial antennas, leading to limitations in isolating transmit and receive signals effectively in frequency-division duplexing systems.
Innovation Solution
The implementation of an electrical balance duplexer circuit with a hybrid transformer and tunable impedance circuit, coupled with filters at either the transmit or receive ports, allows for improved isolation by attenuating signals at specific frequencies, reducing the complexity of the tunable impedance circuit and enabling better power flow and signal cleanliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed-frequency filters are used to isolate transmit and receive signals at different frequency bands, then signal isolation is improved, but device complexity and cost increase due to the need for multiple filters per band
Solution Approach 1:
The patent applies a single electrical balance duplexer (EBD) circuit to replace multiple fixed-frequency filters, enabling one component to perform the isolation function across multiple frequency bands. The EBD uses a hybrid transformer with a tunable impedance circuit that can be adjusted to provide signal cancellation and isolation at different frequencies, making the system universal rather than requiring separate filters for each band
Solution Approach 2:
The patent employs a tunable impedance circuit within the EBD that can dynamically adjust its impedance characteristics to match different frequency requirements. This dynamic tuning capability allows the same hardware configuration to adapt to multiple frequency bands, replacing the static nature of fixed-frequency filters while maintaining effective signal isolation across varying operational conditions
2Device complexity
If an electrical balance duplexer with tunable impedance circuit is used to support multiple bands, then device complexity is reduced, but isolation bandwidth is limited due to frequency-dependent antenna impedance
Solution Approach 1:
The tunable impedance circuit dynamically adjusts the balance network impedance to match the frequency-dependent antenna impedance across different bands. By continuously or step-wise tuning the impedance parameters, the system maintains effective signal cancellation and isolation over a broader frequency range than a fixed impedance configuration would allow
Solution Approach 2:
The patent changes the impedance parameters of the balance network through the tunable impedance circuit to compensate for the frequency-dependent characteristics of the antenna. By adjusting resistance, inductance, and capacitance values in the balance network, the system adapts to different frequency conditions and extends the effective isolation bandwidth across multiple frequency bands
3Reliability
If the tunable impedance circuit is designed for high isolation at both transmit and receive frequencies, then signal isolation is improved, but the circuit design becomes more complex and harder to tune
Solution Approach 1:
The patent segments the isolation function into two separate operational modes: transmit frequency isolation and receive frequency isolation. The EBD is configured to prioritize isolation at one frequency while using filters at the other frequency to handle isolation requirements. This segmentation divides the complex dual-frequency isolation problem into manageable single-frequency optimization tasks, reducing the overall circuit complexity
Solution Approach 2:
The patent applies partial isolation through the EBD at one frequency and complementary filtering at the other frequency, rather than requiring the EBD to provide full isolation at both frequencies simultaneously. This partial action approach reduces the tuning complexity of the EBD while still achieving sufficient overall isolation performance through the combined effect of the EBD and filters
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 configuration simplifies the design of the tunable impedance circuit, reduces signal losses, and maintains high isolation at both transmit and receive frequencies, enhancing the overall performance of the front-end module by allowing for flexible tuning and reduced complexity in the balance network.
Implementation Method 1
They operate based on signal cancellation using a hybrid transformer, essentially by 'balancing' an antenna ZANT and a tunable impedance circuit, the so-called balance network or ZBAL.
Data Source
AI summary
The present disclosure relates to a front-end module for a telecommunication device with an EBD circuit comprising a hybrid transformer for coupling via a transmit port to the telecommunication device transmitting a first frequency transmit signal, to an antenna, via a receive port to the telecommunication device receiving a second frequency receive signal, and to a tunable impedance circuit. In a first configuration the EBD circuit is configured to isolate the transmit port from the receive port at the first frequency, and the FEM comprises a first filter at the transmit port for attenuating the transmit signal with a predetermined amount at the second frequency. In a second configuration the EBD circuit is configured to isolate the transmit port from the receive port at the second frequency, and the FEM comprises a second filter at the receive port for attenuating the receive signal a predetermined amount at the first frequency.