Frequency-Tuning Matching Network
APEC 2024 Best Presentation Award
We propose a general method to design two-port matching networks that can match a varying impedance to a near-constant value by adjusting the frequency. The matching network consists of two stages: a frequency-tuning resistance compression network and a reactance neutralization network. An example circuit is implemented to drive a practical varying plasma impedance while achieving less than 0.12 reflection coefficient within 0.6 MHz tuning bandwidth.
50 MHz Class Φ2 Power Amplifier
IMS SDC 2023 First-place Design
We present the first-place design for the Student Design Competition (SDC) High-Efficiency Power Amplifier for 50 MHz in the 2023 IEEE Microwave Theory and Techniques Society International Microwave Symposium (IMS) in San Diego, California.
High-Voltage DC-DC Converter for Ion Pumps
APEC 2023 Best Presentation Award
Ion pumps rely on high-voltage power supplies with low output ripple to generate ultra-high vacuum. We present a 2 to 7 kV DC power supply with less than 10 Vpp voltage ripple designed for such applications. The circuit utilizes high-frequency inverters, planar PCB transformers, Dickson voltage multipliers, and ripple cancellation. The implemented 80 W prototype can maintain 0.1% ripple while achieving 86% peak efficiency.
13.56 MHz Class DE Power Amplifier
IMS SDC 2021 First-place Design
High-efficiency power amplifiers are critical for various applications that require high power density, portability, and effortless thermal management. Historically, these types of PAs, operating in the tens-of-megahertz range in the industrial, scientific, and medical bands, were equipped for transmitters for fixed radiocommunication services, RF heating, and plasma ignition. Today, applications have expanded to wireless power transmission for biomedical devices and charging for consumer electronics and smart vehicles. We present the first-place design for the Student Design Competition (SDC) High-Efficiency Power Amplifier for 13.56 MHz in the 2021 IEEE Microwave Theory and Techniques Society International Microwave Symposium (IMS) in Atlanta, Georgia.
Resonant Gate Driver for SiC MOSFETs
COMPEL 2021 Best Paper Award
High power and high-frequency converters for compact power systems have been advanced by the recent development of wide bandgap semiconductor devices. In high power applications, silicon carbide (SiC) devices are reliable with high breakdown voltages but suffer from challenging gate drives at high frequency. We develop a resonant gate driver that can effectively reduce the gate loss at high frequency with broad bandwidth. A 13.56 MHz prototype is demonstrated to achieve a 60% loss reduction for a SiC MOSFET.
Cascode GaN/SiC Device
Wide Bandgap (WBG) power semiconductors are being incorporated in an ever widening range of applications. Available Gallium Nitride (GaN) devices have lower voltage ratings than those made of Silicon Carbide (SiC), but the size and construction of GaN devices result in smaller device capacitance that make them easier to drive at higher frequencies. We develop a WBG high-voltage GaN/SiC cascode device, combining the advantages of both a GaN and a SiC device: simple gate drive requirements, losses in the device capacitance per cycle roughly independent of frequency, and relatively high voltage blocking capability. This cascode device is capable of blocking 1.2 kV, while consuming 558 mW at the gate when operating at 13.56 MHz. A 700 W Class E inverter implemented with the proposed cascoded device achieves 91% efficiency at 13.56 MHz.