Active phased array antennas (APAAs), which enable electrical beam forming, have been applied to radar systems and communication systems. As APAAs require thousands of T/R (transmit/receive) modules, the cost of T/R modules accounts for a large portion of the system cost. There is an increasing demand for cost-effective T/R modules with high-performance characteristics. To realize high output power and efficiency, GaN-on-SiC (gallium nitride on silicon carbide) high power amplifiers (HPAs) and switches (SWs) are widely utilized. A major contributing factor to the cost of T/R modules is the cost of the GaN-on-SiC monolithic microwave integrated circuits (MMICs) because of the relatively expensive SiC wafer.

This paper discusses the cost reduction of chipsets consisting of the GaN MMIC DA (driver amplifiers), HPAs, and SW in the T/R module. First, the GaN-on-Si MMIC process is applied to lower the wafer cost. Second, low-loss, low-cost GaAs (gallium arsenide) MMIC matching circuits are combined with the GaN MMIC.
GaN chipsets for cost-effective X-band 20 W T/R modules are fabricated and measured. The chipsets include four devices, a GaN-on-Si MMIC DA, a GaN-on-SiC MMIC HPA with GaAs MMIC input and output matching circuits, a high-gain GaN-on-Si HPA with a GaAs output matching circuit and a GaN-on-Si high power SW. The developed chipsets are estimated to be about half the cost of a conventional chipset while maintaining comparable performance.
These results greatly contribute to the cost reduction of the T/R modules that compose the APAAs. Therefore, this paper is highly evaluated as a paper worthy of the Society's Paper Award.