GaN Semiconductor Device Segmented Gate Drive for Noise Reduction
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Solution Overview
Problem
Existing GaN-based power semiconductor devices face challenges in implementing normally-off operation, which is crucial for safety in high-voltage power supply circuits, due to parasitic capacitance and shared source inductance issues, leading to delays and ringing in power semiconductor devices.
Innovation Solution
A semiconductor device configuration that includes a normally-off transistor, a normally-on transistor, a second normally-off transistor, diodes, and a capacitor, with a gate drive circuit and resistor design that prevents shared source inductance between the main circuit current and gate driving current, ensuring noise reduction and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a normally-on GaN-based transistor is used to achieve high breakdown voltage and high-speed driving, then power semiconductor device performance is improved, but normally-off operation cannot be implemented which is required for safety
Solution Approach 1:
The patent divides the transistor structure into multiple segments: a normally-on GaN-based transistor and one or more normally-off transistors (Si-based or GaN-based) connected in series. This segmentation allows the system to combine the high-performance characteristics of normally-on GaN devices with the safety requirements of normally-off operation, as the normally-off transistor acts as a safety gate that must be actively turned on.
Solution Approach 2:
The patent introduces normally-off transistors as intermediary elements between the normally-on GaN transistor and the load. These intermediary transistors serve as safety controllers that prevent direct connection of the normally-on device to the load, ensuring that power flow is controlled and can be safely interrupted when needed.
2Device complexity
If main circuit current and gate driving current share a source inductance, then circuit complexity is reduced, but delay and ringing occur due to electromotive force modulation
Solution Approach 1:
The patent segments the current paths by providing separate source inductances for the main circuit current and the gate driving current. The main circuit current flows through a first source inductance, while the gate driving current flows through a second source inductance. This segmentation prevents the electromotive force generated in one inductance from modulating the other current, eliminating delay and ringing issues.
Solution Approach 2:
The patent introduces a dedicated second source inductance as an intermediary element specifically for the gate driving current path. This separate inductance acts as a buffer that isolates the gate driving signal from the main circuit current variations, preventing cross-modulation and ensuring clean, fast switching transitions.
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 configuration enables reliable normally-off operation, reduces noise, and improves the rising and falling speeds of power semiconductor devices by maintaining the 'on' state of normally-off transistors earlier than normally-on transistors, thus enhancing the performance and safety of high-voltage power supply circuits.
Implementation Method 1
a capacitor having a first end portion connected to the first anode and the second control electrode and a second end portion
Implementation Method 2
a first diode having a first anode electrically connected to the second control electrode and a first cathode electrically connected to the third electrode
Data Source
AI summary
A semiconductor device of embodiments includes a first normally-off transistor having a first electrode, a second electrode, and a first control electrode, a normally-on transistor having a third electrode electrically connected to the second electrode via a first wiring, a fourth electrode, and a second control electrode, a second normally-off transistor having a fifth electrode, a sixth electrode electrically connected to the third electrode via a second wiring, and a third control electrode, a first diode having a first anode electrically connected to the second control electrode and a first cathode electrically connected to the third electrode, and a capacitor having a first end portion connected to the first anode and the second control electrode and a second end portion.