Hybrid Coupler T/R Switch for Balanced Amplifier Mismatch
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Solution Overview
Problem
Time-division multiplexed (TDM) systems face performance issues due to the introduction of mismatch and power dissipation by the T/R switch, leading to signal attenuation and mismatch conditions between the antenna and amplifiers, which negatively affect system performance.
Innovation Solution
A circuit arrangement utilizing a balanced amplifier with an output hybrid coupler and shunting switches that control the operation as a hybrid coupler-based switch, eliminating the need for a series-connected T/R switch by switching between transmission and reception states to minimize insertion loss and maintain performance advantages of balanced amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a T/R switch is used to connect and disconnect transmit and receive paths to a common antenna, then switching between transmission and reception is enabled, but signal loss increases and mismatch conditions occur between the antenna and amplifiers
Solution Approach 1:
The patent extracts the T/R switch from the signal path by using a hybrid coupler that inherently provides transmit/receive switching through its coupling structure. The hybrid coupler separates the transmit and receive paths using its directional coupling properties, eliminating the need for a separate T/R switch that causes signal loss and mismatch.
Solution Approach 2:
The hybrid coupler performs multiple functions simultaneously: it acts as a power splitter during transmission, a combiner during reception, and provides inherent T/R switching functionality. This multi-functionality eliminates the need for separate dedicated components for each function, reducing overall signal loss and mismatch.
2Reliability
If a T/R switch is used to protect the receive path from high power transmit signals, then isolation between transmit and receive paths is improved, but insertion loss increases and system performance deteriorates
Solution Approach 1:
The hybrid coupler acts as an intermediary device that provides natural isolation between transmit and receive paths through its directional coupling properties. The coupled and isolated ports of the hybrid coupler inherently prevent high power transmit signals from reaching the sensitive receive path without requiring a separate T/R switch, thus maintaining isolation while minimizing insertion loss.
3Ease of operation
If a series-connected T/R switch is used in the transmit path, then switching functionality is achieved, but mismatch conditions are introduced between the antenna and balanced amplifier
Solution Approach 1:
The patent merges the T/R switching function with the hybrid coupler structure itself. The hybrid coupler's inherent directional coupling provides the switching functionality while maintaining proper impedance matching throughout the signal path, eliminating the mismatch conditions that would be introduced by a separate series-connected T/R switch.
Data Source
AI summary
A hybrid coupler-based T/R switch for use in a TDM system. An output hybrid coupler of a balanced amplifier is used to selectively switch a transmit or receive path to an antenna. During transmission, power at the output of the balanced amplifier is delivered directly to the antenna. During reception, power from the antenna is reflected through ports of the hybrid coupler connected to respective two amplifiers of the balanced amplifier, to constructively combine at a port of the coupler coupled to the receive path, with a ninety degrees phase shift. A pair of shunting switches coupled to the ports of the hybrid coupler connected to the two amplifiers, and a shunting switch coupled to the port coupled to the receive path, control operation of the hybrid coupler-based T/R switch.