Impedance-Tuned T/R Separation Circuit for Low-Loss TDD Isolation
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Solution Overview
Problem
The introduction of a switch in the switch circuit for transmission/reception isolation in TDD mode communications devices increases loss on the transmit channel, reducing transmission efficiency.
Innovation Solution
A transmission/reception separation circuit that uses impedance adjustment circuits to isolate the receive channel from the transmit channel without introducing a switch, employing hybrid connection of capacitors and inductors or microstrip circuits to maintain high impedance states during signal transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch circuit is used for transmission/reception isolation in TDD mode, then channel isolation is achieved, but loss on the transmit channel increases and transmission efficiency decreases
Solution Approach 1:
The patent extracts the switch element from the transmit channel by placing it in parallel with the transmit signal path. The switch is configured to open during transmit slots, effectively removing it from the signal path and eliminating its associated loss. This allows the transmit channel to operate without the switch element while still achieving reception isolation through the switch's open state blocking the receive channel.
Solution Approach 2:
The patent introduces an intermediary approach by using the switch element as a mediator that operates in a different configuration than traditional isolation circuits. The switch element, when open during transmit slots, acts as an intermediary that blocks the receive channel without interfering with the transmit channel, thereby achieving isolation without the traditional lossy switch placement.
2Reliability
If a switch is introduced into the switch circuit for transmission/reception isolation, then receive channel isolation is achieved, but transmission efficiency is reduced
Solution Approach 1:
The patent extracts the switch element from the transmit channel signal path by configuring it to open during transmit slots. This removal of the switch from the critical signal path eliminates the loss and efficiency penalty while maintaining the isolation function through the switch's open state blocking the receive channel path.
Solution Approach 2:
Instead of placing the switch in series with the transmit channel for isolation (which causes loss), the patent inverts the approach by placing the switch in parallel and using its open state to achieve isolation. This inversion allows the transmit channel to operate without the switch element, thereby maintaining transmission efficiency while still achieving receive channel isolation.
Data Source
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AI summary
A transmission/reception separation circuit, a transceiver, and a wireless communications device are disclosed. The transmission/reception separation circuit includes a transmission amplification circuit, an impedance adjustment circuit, and a reception amplification circuit. An output end of the transmission amplification circuit is connected to a first end of the impedance adjustment circuit, a second end of the impedance adjustment circuit is connected to an input end of the reception amplification circuit, and the second end of the impedance adjustment circuit and the input end of the reception amplification circuit are further configured to be connected to an antenna. The transmission amplification circuit is configured to amplify a first signal to be transmitted by using the antenna, and the reception amplification circuit is configured to amplify a second signal received by using the antenna. When the antenna transmits the amplified first signal, a first impedance is in a high impedance state. The first impedance is an impedance seen from the input end of the reception amplification circuit. The impedance adjustment circuit is configured to adjust a second impedance to a high impedance state when the antenna receives the second signal. The second impedance is an impedance seen from the second end of the impedance adjustment circuit.