具改進式閘級驅動器之增強型單晶氮化鎵升壓轉換器控制晶片

Abstract

基於氮化鎵元件之轉換器有機會達成如高切換頻率與高效率等優勢，然若以傳統之離散式元件實現轉換器，則轉換器會因為印刷電路板的寄生電感影響切換特性跟效率。在本論文中提出了一個整合氮化鎵功率開關(PowerMOS)、功率二極體、閘級驅動器、運算放大器、比較器之單晶氮化鎵積體電路，實現閉迴路控制之升壓型轉換器。此外，所提的改進閘級驅動器不僅透過內部設計自舉式電路，能使其輸出電壓範圍接近該子電路電源電壓，減少功率元件導通損耗；同時還在閘級驅動器電路架構中避免使用任何電阻來加快開啟及關閉功率元件之時間。所提之具有改進閘級驅動器的單晶氮化鎵控制晶片(Integrated Circuit, IC)使用了TSMC的0.5-μm GaN製程製作，並且有著最高1MHz的切換頻率，輸入電壓為48V和輸出電壓為72V。根據實驗結果可以得到，在140mA負載下，整體效率可以達到96%。

GaN-based converters have the potential advantages of high switching frequency and high efficiency. However, for the implementation of traditional discrete components, the parasitic components, especially the parasitic inductance of the printed circuit board (PCB) would greatly affect the switching performance and efficiency. This thesis presents a monolithic enhancement-mode GaN IC consisting of a power MOS, Power Diode, GaN-based comparator, GaN-based OPA, and gate driver for a boost converter. This thesis achieves the close-loop control for the boost converter. The proposed improved gate driver not only uses an internal bootstrap circuit to fully turn on the GaN power device and reduce conduction loss but also improves the output rising (falling) time by avoiding using any of resistors. Finally, the measurement result verifies that the implemented functions are feasible in boost converter with the close-loop control. This proposed monolithic GaN IC was fabricated in the TSMC 0.5-μm GaN process and experimentally verified that achieves an efficiency of about 96% at load 140 mA in a high conversion ratio. For the proposed boost converter, the conversion ratio is up to 48V to 72V.