TDD Switch Isolation Using Transmission Line Stubs
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Solution Overview
Problem
Conventional TDD switches using circulators fail to effectively isolate the receive port when errors occur, leading to potential damage from high-power transmission signals, and require additional hardware that increases size and complexity.
Innovation Solution
A TDD switch design that employs isolators, λ/4 transmission lines, and transmission line stubs to manage impedance and isolate the receive port without using a circulator, ensuring protection during both transmission and reception modes, even when the system operates abnormally.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circulator is used in the TDD switch, then the receive port can be isolated during transmission mode, but the device size and complexity increase
Solution Approach 1:
The patent extracts and removes the circulator component from the TDD switch structure, replacing it with a simpler transmission line and stub configuration that achieves the same isolation function without the complexity of a three-port circulator device
Solution Approach 2:
The patent uses transmission line stubs that replicate the isolation function of the circulator through impedance transformation and signal reflection principles, creating a functional copy that is structurally simpler and more compact
2Reliability
If a circulator is used in the TDD switch, then the receive port can be isolated during transmission mode, but the system size increases
Solution Approach 1:
The patent removes the bulky circulator component and replaces it with planar transmission line structures that occupy significantly less space while maintaining the same receive port isolation functionality
Solution Approach 2:
The transmission line stubs are designed to be integrated within the existing switch architecture, nesting the isolation function within the transmission path rather than requiring separate external components
3Productivity
If the TDD switch operates in reception mode, then the reception signal can be transmitted to the receiver, but the receiver is vulnerable to high-power transmission signals when errors occur
Solution Approach 1:
The patent implements preliminary protective measures by designing the transmission line and stub configuration to automatically reflect high-power transmission signals back toward the transmitter even when the switch is in reception mode, preventing potential receiver damage before it can occur
Solution Approach 2:
The transmission line stubs are pre-configured with specific impedance values that create a protective buffer, absorbing or reflecting excessive power signals before they can reach and damage the sensitive receiver components
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 effectively isolates the receive port from high-power transmission signals and reduces system size and complexity by eliminating the need for a circulator, while maintaining high isolation performance.
Implementation Method 1
a first transmission line which is connected between the isolator and an antenna feed line, for transmitting a transmission signal received from the isolator to the antenna feed line when in a transmission mode and for isolating a transmission path when in a reception mode
Implementation Method 2
a first transmission line stub which is connected in a stub form between the isolator and the first transmission line for reflecting the transmission signal transmitted from the isolator in the transmission mode and for changing an impedance of the first transmission line in the reception mode
Implementation Method 3
an isolator connected to an output port of a transmitter, a first transmission line which is connected between the isolator and an antenna feed line
Implementation Method 4
a second transmission line connected between an output port of the first transmission line and an input port of a receiver for isolating a reception path in the transmission mode and for providing a reception signal received from the antenna feed line to the receiver in the reception mode
Implementation Method 5
a second transmission line stub connected in a stub form between the second transmission line and the input port of the receiver, for controlling the second transmission line to isolate the reception path when in the transmission mode and for supplying the reception signal provided from the antenna feed line to the receiver when in the reception mode
Data Source
AI summary
A Time Division Duplex (TDD) wireless communication system includes a switch connected to an output port of a transmitter, a first transmission line for transmitting a transmission signal and for isolating a transmission path according to a mode, a first transmission line stub connected between the isolator and the first transmission line for reflecting a transmission signal transmitted from the isolator, a second transmission line connected between an output port of the first transmission line and an input port of a receiver for isolating a reception path in the transmission mode and for providing a reception signal received from the antenna feed line to the receiver, and a second transmission line stub connected in a stub form between the second transmission line and the input port of the receiver, for controlling the second transmission line to isolate the reception path.