Kazuhiro Yahata

1.2kW power combiner unit using phase control for 2.4GHz band

The microwave power source is widely used for heating and dryness, etc. so far. To solve problem (high voltage and short life time, difficult control) of the magnetron used now, semiconductor (GaN-HEMT, LDMOS) is examined. It is necessary to combine several modules to get 1kW, because the output power of semiconductor devices is about 200W. When output power and phase of each module are different, we analyzed the combined output power. We achieved 1.2kW output power by controlling the output of each module.

First pass design of a high power 145W, high efficiency class-J GaN power amplifier using waveform engineering

This paper presents a high power, high efficiency RF power amplifier using GaN on Si heterojunction field effect transistor (HFET) designed using waveform engineering. To investigate the high efficiency operation of the GaN HFET, waveform engineering, employing harmonic active load-pull measurements is conducted, yielding 79W output power and 73.9% drain efficiency under class-J operation. The realized PA based on a larger periphery is designed using a scaled optimum output impedance obtained during the HFET investigation, and exhibits 145W output power and 73.8% drain efficiency with drain bias of 40V under 1/10 pulse measurement conditions. The presented PA is promising for application in RF base station systems.