Coupled-Inductor SP4T RF Switch for Low Loss and High Isolation
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Solution Overview
Problem
The challenge in millimeter wave integrated circuits is to design a miniaturized radio frequency switch that achieves low insertion loss and high isolation degree, which is essential for efficient switching between receiving and transmitting states while meeting the demands of miniaturization.
Innovation Solution
A multi-coil coupling-type single-pole four-throw switch is developed, incorporating a coupled inductor circuit and a transistor-based control circuit that isolates output ports and configures load matching using inductor coils and control circuits, allowing selective electrical conduction among different circuits, thereby reducing insertion loss and enhancing isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional switch design is used, then the isolation degree between ports is achieved, but the insertion loss is high and the device size is large
Solution Approach 1:
The patent combines multiple inductor coils into a coupled inductor circuit where coils are magnetically coupled to each other. This merging of multiple inductive elements into a single integrated circuit structure reduces the overall device area while maintaining the isolation performance, and the coupled structure enables load matching functionality that reduces insertion loss.
Solution Approach 2:
The coupled inductor circuit serves multiple functions simultaneously: it provides isolation between output ports through magnetic coupling, performs load matching for selected output ports, and enables miniaturization through integrated structure. This multi-functionality resolves the contradiction by achieving low insertion loss and high isolation without increasing device complexity.
2Area of stationary object
If the switch is miniaturized, then the device size is reduced, but the isolation degree and insertion loss performance deteriorate
Solution Approach 1:
The patent implements a nested structure where multiple inductor coils are coupled together in a compact arrangement. The coupled inductor circuit nests multiple functional elements (isolation paths, load matching paths) within a single integrated structure, achieving miniaturization while maintaining isolation degree through the magnetic coupling mechanism between nested coils.
3Area of stationary object
If the switch is miniaturized, then the device size is reduced, but the insertion loss increases
Solution Approach 1:
The patent combines multiple inductor coils into a coupled inductor circuit where coils are magnetically coupled to each other. This merging of multiple inductive elements into a single integrated structure reduces the overall device area while maintaining the isolation performance, and the coupled structure enables load matching functionality that reduces insertion loss.
Solution Approach 2:
The patent changes the electrical parameters of the output ports by using the coupled inductor circuit to configure different load conditions. By adjusting the coupling between inductor coils and connecting them to different output ports, the impedance matching is optimized, thereby reducing insertion loss while maintaining the miniaturized structure.
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 achieves high isolation degrees and low insertion loss, enabling a miniaturized switch that can efficiently switch between different circuits, supporting a wide frequency range with improved isolation and reduced mismatch, suitable for millimeter wave integrated circuits.
Implementation Method 1
a coupled inductor circuit, including inductor coils electrically connected with the input port, the first output port, the second output port, the third output port and the fourth output port, wherein the coupled inductor circuit is configured to isolate the first output port, the second output port, the third output port and the fourth output port
Implementation Method 2
configuring a load of the selected one of the first through fourth output ports by using the inductor coils electrically connected with the first through fourth output ports to thereby achieve a load matching for the selected one of the first through fourth output ports
Data Source
AI summary
A multi-coil coupling-type single-pole four-throw (SP4T) switch includes: an input port and first through fourth output ports; a coupled inductor circuit including inductor coils electrically connected with the input port and the first through fourth output ports; and a transistor-based control circuit including control circuits electrically connected with the first through fourth output ports respectively. The transistor-based control circuit is configured for selecting one of the first through fourth output ports to be conducted with the input port based on level signals of the control circuits, and configuring a load of the selected output port by using the inductor coils connected with the first through fourth output ports and the control circuits connected with the others of the first through fourth output ports. Therefore, the multi-coil coupling-type SP4T switch can realize selective electrical conductions among different circuits and achieve low insertion loss, high isolation degree and miniaturization.