GaN-on-Si Series Switching for High Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power semiconductor field effect transistors (FETs) based on silicon struggle to extend the operational voltage range beyond their breakdown voltage, limiting their application in high-power systems requiring large electrical power transmission.
Innovation Solution
A series connection of GaN on Si substrate switching units is implemented, where each transistor's source is connected to the drain of the next transistor, with an external high-resistance resistor to the Si substrate, and an internal voltage-controlled resistance in the epitaxial buffer layer, maintaining a consistent voltage drop across each transistor to enhance the voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional silicon-based power FETs are used, then the device structure is simple and easy to manufacture, but the operational voltage range is limited by the breakdown voltage
Solution Approach 1:
The patent divides the power switching function into multiple GaN FET units connected in series, where each unit operates at a lower voltage (e.g., 650V) but the series combination achieves higher total voltage capability (e.g., 1200V, 1700V, or 3500V). This segmentation allows each transistor to be manufactured with standard processes while the system achieves extended voltage range.
Solution Approach 2:
The patent employs GaN on Si substrate technology, combining the advantages of GaN material (high breakdown voltage, high electron mobility) with silicon substrate (成熟的制造工艺, large diameter wafer availability). This composite approach enables high-voltage operation with manufacturable device structures.
2Adaptability or versatility
If multiple switching units are connected in series to extend voltage range, then the operational voltage range increases, but the device complexity increases
Solution Approach 1:
The patent integrates multiple GaN FET units into a single monolithic device structure on one chip, combining their series connection functionality within a unified package. This merging approach reduces the overall system complexity compared to using discrete components, while maintaining the extended voltage range capability.
Solution Approach 2:
The patent designs the series-connected GaN FET units to share common control and support structures, allowing a single device to handle multiple voltage levels (650V, 1200V, 1700V, 3500V) by simply changing the number of units in series, providing universal high-voltage switching capability.
3Adaptability or versatility
If high voltage switching is achieved through series connection, then the voltage range extends to 1200V-3500V, but energy losses increase
Solution Approach 1:
The patent exploits the superior material parameters of GaN (higher electron mobility, higher saturation velocity, higher breakdown field) compared to silicon to reduce on-resistance and switching losses. Even with multiple units in series, the overall energy loss remains lower due to GaN's inherent material advantages.
Solution Approach 2:
The patent leverages the natural characteristics of GaN FETs (normally-off operation, fast switching capability, low parasitic inductance) to achieve efficient high-voltage switching without requiring additional loss-mitigation circuitry, allowing the devices to serve their own efficiency needs.
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
This configuration allows for a significant extension of the operational voltage range, enabling the handling of higher voltages such as 1200V, 1700V, and up to 3500V, while minimizing energy losses and maintaining efficient switching performance.
Implementation Method 1
The source of each first transistor is connected to its Si substrate via an external resistor with high resistance
Implementation Method 2
The drain of each first transistor is connected to an internal, voltage controlled resistance that is formed in the internal buffer layer epitaxial structure of GaN on Si substrate
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus includes a circuitry to perform a high current and/or a high voltage switching. The circuitry includes a first Gallium Nitride (GaN) on a silicon (Si) substrate lateral field effect transistor (Q1). A source terminal of the first GaN lateral field effect transistor on the Si substrate includes an electrical connection to the backside of the P-type Si substrate through a high voltage isolated resistor (R1) that is coupled to a source terminal and a second, voltage controlled resistor (Rv1) that is operably coupled to a drain terminal and a substrate terminal and formed int the internal buffer layer epitaxial structure of the GaN on Si substrate of the first transistor. The high voltage isolated resistor and the second resistor cause a leakage current from the drain terminal to the source terminal via said buffer layer. The leakage current equalizes the voltage drop on the first GaN lateral field effect transistor on the Si substrate to a voltage drop on a serially connected second GaN lateral field effect transistor on the Si substrate.