RF Switch Transistor Layout for Even High-Voltage Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Radio frequency (RF) switches face challenges in withstanding high voltages without breakdown, particularly when multiple transistors are used in series, leading to uneven voltage distribution and potential physical destruction, which can result in impaired on-state characteristics and increased integrated circuit size.
Innovation Solution
The RF switch design incorporates a first transistor closer to the RF signal input with a larger electrode width, more contact vias, and a shorter distance to its control electrode, and a second transistor farther away with fewer contact vias and a smaller electrode width, allowing for adjusted gate lengths and impedance values to evenly distribute voltage across transistors, preventing breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transistors are coupled in series to withstand high voltage, then the breakdown resistance is improved, but the on-state characteristics deteriorate and the integrated circuit size increases
Solution Approach 1:
The patent applies local quality by making each transistor have different characteristics based on its position in the series chain. Specifically, transistors closer to the high-voltage node have larger channel widths and different dimensions compared to those farther away. This localized differentiation allows each transistor to be optimized for its specific voltage stress level, achieving adequate breakdown resistance across the entire series chain while minimizing the total circuit area.
Solution Approach 2:
The patent changes physical parameters of the transistors, specifically the channel width and length, based on their position in the series configuration. Transistors experiencing higher voltage stress have larger channel widths to distribute the voltage more effectively, while those with lower stress have smaller dimensions. This parameter variation allows the series chain to withstand high voltage without requiring all transistors to be oversized, thus reducing the overall integrated circuit size.
2Reliability
If multiple transistors are used in series to prevent breakdown, then the voltage withstand capability is improved, but the on-state characteristics are deteriorated
Solution Approach 1:
The patent implements local quality by assigning different channel widths to transistors based on their position in the series chain. Transistors closer to the high-voltage node have larger channel widths to ensure adequate voltage distribution and prevent breakdown, while transistors farther from the high-voltage node have smaller channel widths. This localized optimization maintains good on-state characteristics (lower resistance) in less stressed regions while ensuring voltage withstand capability in critical regions.
Solution Approach 2:
The patent modifies the channel width parameter of each transistor according to its position in the series configuration. By increasing the channel width of transistors that experience higher voltage stress and decreasing it for those with lower stress, the patent achieves a balance between voltage withstand capability and on-state performance. This parameter optimization ensures that no single transistor becomes the bottleneck for either breakdown resistance or on-state conductivity.
Data Source
AI summary
A radio frequency (RF) switch is provided. The RF switch is configured to switch a RF signal input to a first terminal. The RF switch includes a first transistor, disposed at a first distance from the first terminal, and configured to switch the RF signal, and a second transistor, disposed at a second distance from the first terminal, and configured to switch the RF signal. The first distance is shorter than the second distance, and a number of first contact vias formed in a first electrode in the first transistor is greater than a number of second contact vias formed in a second electrode of the second transistor.