Efficient High Power Pulsed Radar Amplifiers: Drain Versus Gate Modulations in GaN Technology

Attributed to its superior performance, gallium nitride (GaN) technology is transforming the way pulsed radar power amplifiers (PAs) are designed. Nevertheless, the performance of GaN PAs can be degraded by charge-trapping and temperature effects, necessitating the development of appropriate driving and power-supplying techniques. In this letter, we demonstrate the advantages of drain-modulated GaN PA over the gate-modulated GaN PA, with or without pulsed continuous wave (CW) drive. For this comparison, we focus on the output power and efficiency—key metrics for a high-performance radar transmitter. It is shown that the lower gate voltage peaks and nearly zero dc power dissipation during the “off” time in a drain-modulated PA result in 10%–14% more output power and 5%–6% points higher efficiency compared with gate modulation of the same PA.