Three-Port Inductor T/R Switch for Low-Loss Receiver Protection
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Solution Overview
Problem
Existing transmit-receive (T/R) switches with series-coupled switches suffer from insertion loss, linearity issues, and reliability problems, degrading receive sensitivity and power efficiency, and potentially damaging receiver devices due to power amplifier signal leakage.
Innovation Solution
A T/R switch configuration that includes a three-port inductor and transistors, where the receive path is pulled down to ground during receive mode and powered by a pull-up transistor during transmit mode, and optionally uses a transformer in the transmit path, eliminating series-coupled switches to reduce insertion loss and improve linearity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If series-coupled switches are used in T/R switch paths, then switching between transmit and receive modes is enabled, but insertion loss increases and receive sensitivity degrades
Solution Approach 1:
The patent removes series-coupled switches from the signal path entirely. Instead of using switches in series to control signal flow between transmit and receive modes, the invention extracts the switching function and replaces it with parallel paths using shunt switches that connect to ground, eliminating the insertion loss caused by series switch resistance while maintaining reliable mode switching.
Solution Approach 2:
The patent introduces an intermediary switching mechanism using shunt switches connected to ground references rather than series switches in the signal path. This intermediary approach allows mode switching to occur without placing resistive elements directly in the signal flow, thereby reducing insertion loss while maintaining switching reliability.
2Reliability
If series-coupled switches are used in T/R switch paths, then mode switching is achieved, but linearity deteriorates
Solution Approach 1:
The patent extracts series switches from the signal path where they degrade linearity. By removing these non-linear switching elements from the main signal flow and replacing them with shunt switches connected to ground, the invention maintains switching reliability while preserving signal linearity throughout the transmit and receive paths.
3Ease of operation
If series-coupled switches are used in T/R switch paths, then switching function is provided, but receiver devices may be damaged by power amplifier signal leakage
Solution Approach 1:
The patent converts the potential harmful effect of signal leakage into a protective mechanism by using shunt switches that actively connect high-impedance paths to ground during transmit mode. This configuration deliberately creates a low-impedance path for any leaked power amplifier signals, safely directing them to ground rather than allowing them to damage sensitive receiver devices.
Solution Approach 2:
The patent introduces shunt switches as intermediary protective elements between the transmit path and receiver devices. These switches act as mediators that can rapidly connect suspicious or leaked signals to ground references, preventing harmful signals from reaching sensitive receiver components while maintaining normal switching operation.
4Reliability
If series-coupled switches are used in T/R switch paths, then transmit-receive switching is enabled, but power efficiency decreases
Solution Approach 1:
The patent extracts series switches from the signal path where they consume power through their on-resistance. By replacing them with shunt switches connected to ground, the invention eliminates the continuous power loss associated with series switch resistance while maintaining the ability to reliably switch between transmit and receive modes.
Data Source
AI summary
A transmit-receive (T/R) switch is disclosed. An apparatus including a T/R switch includes a transceiver to transmit signals to an antenna and to receive signals from the antenna. The signals are conveyed to and from the transceiver by a T/R switch. The T/R switch includes a transmit path and a receive path. The receive path includes a three-port inductor having a first terminal coupled to an input/output (I/O) terminal of the T/R switch and a second terminal coupled to a first pass transistor, and a third terminal. A pull-down transistor is coupled between the third terminal and a ground node. When active, the pull-down transistor pulls the receive path down toward ground.