Transformer Gate Driver Layout for Clean GaN HEMT Switching
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Solution Overview
Problem
Gallium nitride high-electron-mobility transistors (GaN HEMTs) are susceptible to unexpected turn-on due to electromagnetic interference (EMI) and noise, causing large voltage spikes and complex layout issues, especially when the auxiliary power supply and gate driver circuit are separated, leading to increased parasitic inductances and noise susceptibility.
Innovation Solution
Incorporating a transformer between the auxiliary power supply and gate driver circuit to shorten gate lines and current loops, reducing parasitic inductance and noise susceptibility by decoupling gate currents, and simplifying the layout design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the auxiliary power supply is located far from the gate driver circuit (e.g., on different PCBs), then the circuit layout flexibility is improved, but the lines between the gate driver circuit and auxiliary power supply become susceptible to EMI and noise
Solution Approach 1:
The patent introduces a transformer as an intermediary component between the auxiliary power supply and the gate driver circuit. The transformer couples the power supply to the driver circuit through magnetic coupling, allowing the power supply to be located remotely while maintaining signal integrity and reducing EMI susceptibility through the isolated magnetic coupling path.
2Adaptability or versatility
If the gate-line current loop is made long to accommodate physical layout constraints, then the layout flexibility is improved, but the parasitic inductances increase causing self-turn-on of GaN HEMTs
Solution Approach 1:
The transformer acts as an intermediary that provides galvanic isolation between the power supply ground and the driver circuit ground. This isolation breaks the ground loop that would otherwise form a large parasitic inductance, allowing the physical layout to be flexible while maintaining small effective current loop areas and low parasitic inductances.
3Productivity
If GaN HEMTs are driven with fast switching to achieve high-frequency power conversion, then the power conversion efficiency is improved, but large voltage spikes (large dv/dt) are generated causing increased noise
Solution Approach 1:
The transformer provides magnetic coupling that isolates the fast-switching GaN HEMT circuit from the auxiliary power supply circuit. The magnetic coupling allows power transfer while blocking the propagation of high dv/dt voltage spikes and noise from the switching circuit into the power supply circuit, enabling fast switching without excessive noise generation.
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 transformer-based layout significantly reduces noise and voltage spikes, enabling clean switching with shorter gate lines and current loops, thus improving the reliability and efficiency of GaN HEMT operation.
Implementation Method 1
Incorporating a transformer between the auxiliary power supply and gate driver circuit
Implementation Method 2
reducing parasitic inductance and noise susceptibility by decoupling gate currents
Data Source
AI summary
A switching circuit includes a first switch; a second switch connected in series with the first switch; a first isolated driver connected to a gate terminal of the first switch; a second isolated driver connected to a gate terminal of the second switch; and a transformer including a primary winding connected to an auxiliary power supply, a first secondary winding to supply a first voltage to the first isolated driver, and a second secondary winding to supply a second voltage to the second isolated driver.