Electrical Balance N-Plexer With Dynamic Impedance Matching
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Solution Overview
Problem
Existing electrical balance duplexers face challenges in maintaining impedance balance due to varying antenna impedance, providing isolation at multiple frequencies, power loss, and lack of filtering, which affects the efficiency of wireless communication systems.
Innovation Solution
A circuit design that includes phase inverters and variable filters in both transmit and receive paths, along with a hybrid junction, to split and combine signals effectively, and a variable impedance to match antenna impedance, ensuring isolation and filtering across different frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a variable impedance is tuned to antenna impedance to achieve isolation in an electrical balance duplexer, then transmit-receive isolation is improved, but the system becomes sensitive to antenna impedance variations and difficult to maintain balance
Solution Approach 1:
The patent applies dynamics by making the impedance tuning element variable and controllable. The system uses a variable capacitor or varactor diode that can be dynamically adjusted to match the antenna impedance at different frequencies, allowing the duplexer to adapt to impedance variations while maintaining isolation performance across multiple frequency bands
Solution Approach 2:
The patent changes the electrical parameter (capacitance) of the tuning element to achieve impedance matching. By varying the capacitance value, the system can match the antenna impedance at different operating frequencies, thereby maintaining transmit-receive isolation across multiple frequency bands without requiring separate duplexers for each band
2Reliability
If an electrical balance duplexer is designed for one frequency band, then isolation is achieved at that frequency, but providing isolation at two or more different frequencies becomes difficult
Solution Approach 1:
The patent achieves multi-functionality by designing a single duplexer circuit that can operate across multiple frequency bands. The variable impedance tuning element allows the same circuit topology to provide isolation at different frequencies, making the duplexer universal for multi-band FDD operations without requiring separate duplexers for each frequency band
Solution Approach 2:
The system uses dynamic tuning capability to adapt the impedance matching network for different frequency bands. By controlling the variable capacitor or varactor diode, the system can reconfigure its impedance characteristics to maintain isolation performance whether operating in one frequency band or multiple frequency bands simultaneously
3Reliability
If signal power is split in an electrical balance duplexer, then isolation between paths is achieved, but 3 dB loss occurs in transmit and receive paths
Solution Approach 1:
The patent converts the harmful power loss into a beneficial configuration by using the power split to achieve isolation. The 3 dB loss is accepted as the price for obtaining transmit-receive isolation, but the system optimizes this trade-off by using high-Q resonant circuits and efficient impedance matching to minimize additional losses, thereby converting the isolation mechanism into a net benefit for full-duplex operation
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 design enhances transmit-receive isolation, reduces power loss, and provides selective filtering, improving the efficiency and sensitivity of wireless communication systems by minimizing self-interference and accommodating varying antenna impedances.
Implementation Method 1
a first signal junction having a transmit port for receiving the transmit signal, a receive port for outputting the receive signal, a third port and a fourth port, wherein the third and fourth port are for outputting a pair of common mode or differential mode transmit signals which are split from the transmit signal
Implementation Method 2
a phase inverter connected in a path of one of the pair of differential or common mode transmit or receive signals, wherein the pair of receive signals received at the receiver port are in-phase and the pair of transmit signals received at the antenna port are in-phase
Data Source
AI summary
There is described a circuit for transmitting a transmit signal at a transmit frequency and receiving a receive signal at a receiver frequency, for use with a common antenna, comprising: a first signal junction having a transmit port for receiving the transmit signal, a receive port for outputting the receive signal, a third port and a fourth port, wherein the third and fourth port are for outputting a pair of common mode or differential mode transmit signals which are split from the transmit signal at the transmit port, and for receiving a pair of common mode or differential mode receive signals which are combined and provided to the receive port; a second signal junction having an antenna port for connection to an antenna, a second port and a third port, wherein the second and third port are for outputting the pair of common mode or differential mode receive signals which are split from the signal received at the antenna port, and for receiving the pair of common mode or differential mode transmit signals which are combined and provided to the antenna port; a phase inverter connected in a path of one of the pair of differential or common mode transmit or receive signals, wherein the pair of receive signals received at the receiver port are in-phase and the pair of transmit signals received at the antenna port are in-phase.