SWaP Optimised L -Band Power Amplifier for Airborne Applications

This paper discusses the design and development of a SWaP (size, weight and power) optimized L-Band Power Amplifier for Ground and Airborne applications. GaN transistors the main active high-power element in this amplifier designs for high efficiency. Keysight Advance Design System (ADS) simulation tool is used to design and optimize the input and output matching along with transient & EM simulation of power amplifier. The 3-stage amplifier has been designed using two driver stages and one power stage amplifier. The bias sequencing circuit for GaN is designed using P-channel, N-channel MOSFETs and AND gates. The amplifier has provision of reverse polarity protection and switching on/off by digital controls. This amplifier works with single power supply which can range from 8V-60V and its output can be switched between two antenna ports. With optimized matching networks, more than 4-watt output power, power gain of 15 dB and power added efficiency (PAE) of more than 50% are obtained at carrier frequency of 1200 MHz and band width of 100 MHz of main power stage. The isolation between the two antenna ports is more than 50 db. The amplifier has been designed with thermal compensation for power output of more than 4 watt in the temperature range of - 20°C to +55°C. The hardware realized using mixed four-layer PCB with the total thickness of 1.6 mm on Rogers 4350B and FR-4substrate. The top Layer 20 mil Rogers 4350B is used for RF routing. Components are populated on both side of the PCB due to size constraint. The SWaP optimized amplifier has been realized in mechanical housing with the size of 124 mm x 86 mm x 31.5 mm (LxWxH) and weight of 480 gm with extra mounting studs for fitment.