Adaptive Duo-Gate MOSFET for High Voltage Switching
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Solution Overview
Problem
Trench MOSFETs face increased turn-on resistance and switching loss when used in high voltage operations due to the capacitance generated by the extended gate in Charge-Coupling MOSFETs, which affects power efficiency in switching-mode circuits.
Innovation Solution
The adaptive duo-gate MOSFET incorporates a trench MOSFET with a first and second gate, and an adaptive element that dynamically controls the electrical connection between the gates and the source based on potential differences, reducing capacitance and optimizing breakdown voltage and conduction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the gate is extended to the N-type epitaxial layer to increase breakdown voltage, then the breakdown voltage is improved, but the capacitance from gate to drain is increased resulting in extended switching time and increased switching loss
Solution Approach 1:
The gate is divided into two separate gates: a first gate that extends to the N-type epitaxial layer to generate charge-coupling and increase breakdown voltage, and a second gate positioned at the P-type well to control channel formation. This segmentation allows each gate to perform its specific function independently, resolving the contradiction between achieving high breakdown voltage and maintaining low switching loss.
2Strength
If the first gate is electrically coupled to the source to generate charge-coupling during blocking operation, then the breakdown voltage is improved, but during conduction state the gate cannot accumulate electrons resulting in higher turn-on resistance
Solution Approach 1:
The electrical connection state of the first gate is made dynamic rather than fixed. During blocking operation, the first gate is electrically coupled to the source to generate charge-coupling and increase breakdown voltage. During conduction state, the first gate is electrically connected to the second gate to enable electron accumulation and reduce turn-on resistance. This dynamic switching of connection states resolves the contradiction between achieving high breakdown voltage and maintaining low conduction loss.
3Strength
If the N-type epitaxial layer doping concentration is decreased to enable high voltage operation, then the breakdown voltage is improved, but the turn-on resistance is increased
Solution Approach 1:
The first gate extending to the N-type epitaxial layer acts as an intermediary that generates a two-dimensional charge balance electric field. This electric field enables the N-type epitaxial layer with higher doping concentration to be used in high breakdown voltage applications, thereby simultaneously achieving low turn-on resistance and high breakdown voltage.
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 approach simultaneously reduces switching and conduction losses, enhancing power efficiency in switching-mode circuits by managing gate potential and capacitance effectively.
Implementation Method 1
the first gate is configured to generate charge-coupling in the substrate
Implementation Method 2
the second gate is configured to form a channel in the trench MOSFET
Implementation Method 3
a capacitance from the gate to the drain is increased resulting in the extension in a switching time
Data Source
AI summary
An adaptive duo-gate MOSFET includes a trench MOSFET and an adaptive element. The trench MOSFET includes a source, a drain, a first gate, a second gate, and a dielectric layer between the first and second gates. Herein, the first gate may generate charge-coupling in blocking operation, and the second gate may form channel in the trench MOSFET when in conduction operation. The adaptive element is electrically coupled to the first gate, the second gate, and the source respectively. When a potential difference between the second gate and the source is larger than a predetermined value, the first gate and the source are electrically disconnected and then the first gate and the second gate are electrically connected. After a predetermined time, the first gate and the second gate are electrically disconnected and then the first gate and the source are electrically connected.