RF Switch Branch Structure for Uniform Transistor Voltage Sharing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-power radio frequency (RF) switches face challenges in uniformly distributing RF voltage across a series stack of transistors, leading to transistor breakdown and increased insertion loss due to parasitic capacitances, necessitating additional transistors that occupy more die area.
Innovation Solution
A switch branch structure with a metal layer element capacitively coupling the input terminal to a portion of the series stack of transistors, balancing drain-to-source voltages to prevent transistor breakdown and reduce the number of transistors required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional switch branch structure is used, then the connection between common terminal and branch terminals is achieved, but the internal wiring becomes complex and the number of pins increases
Solution Approach 1:
The switch branch structure is segmented into independent modules, where each switch branch (e.g., SB1, SB2) is a separate unit connected to the common terminal. This segmentation simplifies the internal wiring by avoiding complex interconnections while maintaining reliable signal transmission through dedicated paths for each branch.
Solution Approach 2:
The patent extracts and eliminates redundant pins and wiring from the traditional switch structure. By using a simplified configuration where each switch branch directly connects to the common terminal without requiring additional intermediate connection points, the design reduces the total pin count while preserving the essential switching function and connection reliability.
2Area of stationary object
If more pins are used in the switch structure, then more connection points are available, but the overall size of the switch increases
Solution Approach 1:
The common terminal (S1) serves as a universal connection point that can be connected to any switch branch terminal (e.g., S21, S22) depending on the switching requirement. This multi-functional design allows a single common terminal to replace what would traditionally require multiple dedicated terminals, reducing the overall switch size while maintaining connection flexibility for various circuit configurations.
Solution Approach 2:
Multiple connection functions are merged into a single common terminal structure. Instead of having separate terminals for each possible connection, the patent combines all branch connections to share a common terminal, thereby reducing the total number of pins and the physical footprint of the switch while preserving the ability to establish any required connection path.
3Ease of manufacture
If the switch structure is simplified, then the manufacturing cost decreases, but the signal transmission reliability may be compromised
Solution Approach 1:
The patent applies local quality by ensuring that each switch branch connection point is specifically optimized for reliable signal transmission. While the overall structure is simplified, each local connection (e.g., between common terminal S1 and branch terminal S21) is designed with appropriate contact quality and wiring standards to maintain signal integrity, thus achieving manufacturing simplicity without compromising transmission reliability.
Solution Approach 2:
The common terminal acts as an intermediary that ensures reliable signal transmission between switch branches. This mediator structure provides a standardized, high-quality connection interface that simplifies the overall manufacturing process while guaranteeing consistent signal transmission performance across all switching operations.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A switch branch structure has an input terminal, an output terminal, and a series stack of an N-number of transistors formed in an active device layer within a first plane, wherein a first one of the N-number of transistors is coupled to the input terminal, and an nth one of the N-number of transistors is coupled to the output terminal, where n is a positive integer greater than one. A metal layer element has a planar body with a proximal end that is electrically coupled to the input terminal and distal end that is electrically open, wherein the planar body is within a second plane spaced from and in parallel with the first plane such that the planar body capacitively couples a radio frequency signal at the input terminal to between 10% and 90% of the N-number of transistors when the switch branch structure is in an off-state.