Bidirectional Switching Circuit Shielding for Gate Noise Stability
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Solution Overview
Problem
Bidirectional switching devices with double gates experience unstable switching operations due to gate noise, which is caused by parasitic capacitance between the gate electrodes, leading to potential breakdown and false firing.
Innovation Solution
A bidirectional switching device is designed with first and second shield electrodes that shield the electric field lines between the gate electrodes, reducing parasitic capacitance and stabilizing the switching operation. The shield electrodes are positioned to cover the gate electrodes and are connected to the ohmic electrodes, maintaining their potential, thereby reducing gate noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bidirectional switching device with double gates is used, then the on-state resistance is reduced, but gate noise is generated causing unstable switching operation
Solution Approach 1:
A shield electrode is introduced as an intermediary element between the first gate electrode and the second gate electrode. This shield electrode, connected to a reference potential, mediates the electric field interaction between the two gates, preventing direct capacitive coupling and the resulting gate noise that causes unstable switching operations.
Solution Approach 2:
The harmful parasitic capacitance between the gate electrodes is effectively removed by extracting the electric field lines through the shield electrode. By placing the shield electrode between the gates and connecting it to reference potential, the problematic capacitive coupling is extracted from the circuit, eliminating the source of gate noise.
2Reliability
If shield electrodes are added to reduce parasitic capacitance, then switching stability is improved, but device complexity increases
Solution Approach 1:
The shield electrode serves multiple functions simultaneously: it shields the electric field between gates to reduce parasitic capacitance, provides a reference potential boundary, and can be integrated with existing electrode structures. This multi-functionality achieves switching stability improvement without proportionally increasing device complexity.
Solution Approach 2:
The shield electrode can be merged with existing electrode structures or formed as part of the same fabrication process layer. By combining the shielding function with the existing electrode architecture rather than adding completely separate components, the increase in device complexity is minimized while still achieving the desired switching stability.
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
The solution effectively reduces gate noise and parasitic capacitance, allowing for stable switching operations and preventing false firing, while maintaining a high breakdown voltage.
Implementation Method 1
first and second shield electrodes that shield lines of electric force generated between a first gate electrode and a second gate electrode
Implementation Method 2
charge occurs at a heterojunction interface between aluminum gallium nitride (AlGaN) and gallium nitride (GaN) due to spontaneous polarization and piezoelectric polarization
Implementation Method 3
charge occurs at a heterojunction interface between aluminum gallium nitride (AlGaN) and gallium nitride (GaN) due to spontaneous polarization and piezoelectric polarization
Data Source
AI summary
A bidirectional switching device includes a semiconductor multilayer structure made of a nitride semiconductor, a first ohmic electrode and a second ohmic electrode which are formed on the semiconductor multilayer structure, and a first gate electrode and a second gate electrode. The first gate electrode is covered with a first shield electrode having a potential substantially equal to that of the first ohmic electrode. The second gate electrode is covered with the second shield electrode having a potential substantially equal to that of the second ohmic electrode. An end of the first shield electrode is positioned between the first gate electrode and the second gate electrode, and an end of the second shield electrode is positioned between the second gate electrode and the first gate electrode.