GaN-HEMT Cascode Circuit with Field Plate for Current Collapse
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
GaN-HEMTs experience current collapse and reduced lifespan due to electron trapping and high voltage-induced insulating film deterioration when used in high-frequency and high-voltage applications, particularly with source field plates.
Innovation Solution
A cascode connection circuit incorporating a GaN-HEMT with a field plate and an enhancement mode MOS-FET, coupled with a constant current source to manage leakage current and prevent threshold value variations, thereby reducing electron trapping and insulating film deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a source field plate is provided to the GaN-HEMT to counteract current collapse, then current collapse is suppressed, but the threshold value varies when high voltage is applied to the insulating film, shortening device life
Solution Approach 1:
A depression mode transistor is introduced as an intermediary component between the enhancement mode transistor and the load. This depression mode transistor acts as a mediator that controls the voltage applied to the insulating film beneath the source field plate, preventing excessive voltage stress while maintaining current collapse suppression functionality.
Solution Approach 2:
The invention changes the operational parameters by using a depression mode transistor with different electrical characteristics (normally-on state) compared to the enhancement mode transistor. This parameter change allows the system to maintain the beneficial electric field distribution for current collapse suppression while controlling the voltage stress on the insulating film to prevent threshold value variation.
2Productivity
If GaN-HEMT is operated at high frequency and high voltage to improve power supply performance, then switching loss is reduced, but electron trapping occurs causing current collapse
Solution Approach 1:
The power switch is segmented into two transistors: an enhancement mode transistor for high-frequency switching control and a depression mode transistor with source field plate for current collapse suppression. This segmentation allows each transistor to specialize in its optimal function, enabling high-frequency operation while maintaining current stability.
Solution Approach 2:
The depression mode transistor serves as an intermediary that stabilizes the current flow by suppressing electron trapping effects. It mediates between the high-frequency switching signals and the physical phenomenon of electron trapping, ensuring current stability during high-frequency and high-voltage operation.
Data Source
AI summary
A power supply circuit includes: a depression mode transistor that includes a field plate; an enhancement mode transistor to which a source electrode and a drain electrode of the depression mode transistor are coupled; and a constant current source that is coupled to a connection node between the depression mode transistor and the enhancement mode transistor.