Research On Key Techniques Of Heterogeneous Integrated Boost Converter Circuits Designs Using Silicon And GaN Technologies

With the development of portable devices and automotive,power supplies devices are required to meet compact size and increasingly stringent power density requirements.Compared with MOSFET,GaN HEMTs have lower on-resistance,smaller input capacitance,and output capacitance under the same voltage rating.These properties lead to much lower switching and conduction losses that increase the system conversion efficiency and enhance reliability.However,GaN-based DC-DC converters are usually produced on the Printed Circuit Board(PCB)platform,which limits the level of integration.Hence,heterogeneous integration technology taking the advantage of both Si MOSFET and GaN HEMT is adopted in power electronics to make power conversion achieve remarkable performance enhancements,including high switching frequency,high conversion ratio,and large output power density.In this article,research on key techniques of heterogeneous integrated boost converter circuits with large output power density have been done based on GaN2BCD platform(U.S.Patent Authorization),in which the GaN transistors are flip-chip soldered directly on the top of the BCD top metallization using the die-to-wafer transfer(D2W)assembly to achieve heterogeneous integration.To reduce power loss,the topology of the synchronous boost converter is chosen.In this prototype,the enhancement mode(normally OFF)EPC2106 GaN FET,which contains two e GaN FETs,is used as high side and low side switch transistors to reduce the volume of the converter and achieve compact size,while the controller implementation is designed with SMIC 0.18μm BCD process.Then,the system characteristics and the small-signal model of this voltage mode pulse width modulator boost converter are analyzed in detail.Function blocks including bandgap reference,Low Dropout Regulator(LDO),error amplifier,oscillator,comparator,and so on,are designed and their characteristics are verified by simulation.According to the system indicators,the size of inductance and capacitor is calculated.Based on the above analysis,the compensation network is designed to keep the stability of this system,and through simulation validated this compensated system.According to the system indicators,the size of inductance and capacitor is calculated.Based on the above analysis,the compensation network is designed to keep the stability of this system.This presented boost converter operates at a switching frequency of 1.8MHz with an input voltage range of 12V～24V and load current range of 0.1A～0.96A.Simulations show this presented boost converter can maintain the output voltage of 48V when changing input voltage or load current and achieves a maximum output power of 46.08W.The peak conversion efficiency of 94.1%is obtained,when the input voltage is 24V.Finally,the layout of this GaN2BCD-based boost converter is finished.The size of the whole chip is 1.76×2.57mm~2,which is 2.5times that of the current similar commercial products(TPS61379),and the comprehensive performance is internationally leading.The chip design technology can be applied to the research of miniaturization,high power density,and high integration of automotive converters.