RF Switch Circuit Layout for High-Isolation MIMO Signal Paths
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Solution Overview
Problem
In multi-input multi-output switch circuits, ensuring isolation between signal paths is challenging due to crossings or overpass crossings, leading to increased signal interference.
Innovation Solution
A multi-input multi-output switch circuit design that eliminates crossings and overpass crossings by connecting selection terminals to common terminals via nodes, reducing the number of paths and improving isolation through a specific configuration of switches and low-pass filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a multi-input multi-output switch circuit is used to enable simultaneous communication of multiple radio-frequency signals, then the communication capability is improved, but the isolation between signal paths deteriorates due to crossings and overpass crossings
Solution Approach 1:
The switch circuit is divided into multiple independent switching units, each handling specific signal paths. By segmenting the circuit into modular components with dedicated switching elements, the design eliminates unwanted crossings and overpass crossings between paths, thereby maintaining signal isolation while enabling multi-band communication capability.
Solution Approach 2:
Isolation components such as inductors and capacitors are introduced as intermediary elements between signal paths. These components act as mediators to block unwanted signal coupling and interference between paths, ensuring proper isolation is maintained even when multiple signals are transmitted simultaneously through the switch circuit.
2Adaptability or versatility
If multiple switches are used to connect selection terminals to common terminals, then the switching flexibility is improved, but the device complexity increases
Solution Approach 1:
The switch circuit employs universal switching elements that can handle multiple signal paths and configurations. Each switching unit is designed to perform multiple functions depending on the control signals applied, allowing the circuit to support various switching patterns (e.g., 1x1, 2x2, 4x4) without requiring separate dedicated switches for each path, thereby reducing overall complexity while maintaining flexibility.
Solution Approach 2:
The switch circuit is organized in a nested hierarchical structure where smaller switching units are combined to form larger switching matrices. This nested architecture allows the circuit to achieve high switching flexibility through modular composition, where each level of nesting reuses the same basic switching building blocks, reducing the total number of unique components needed.
Data Source
AI summary
A switch circuit includes: first through third common terminals; a first selection terminal that can be connected to the first through third common terminals; second and third selection terminals that can be connected to the first and third common terminals via a first node and can be connected to the first and second common terminals via a second node; first through third switches connected between the first through third common terminals and the first selection terminal; fourth through fifth switches connected between the first and third common terminals and the first node; sixth and seventh switches connected between the first and second common terminals and the second node; eighth and ninth switches connected between the second and third selection terminals and the first node; and tenth and eleventh switches connected between the second and third selection terminals and the second node.