In this paper, 35 W driver power amplifier was designed and simulated using GaN HEMT for L-band radar. GaN HEMT is used because it can provide high output power and high gain as compared to other semiconductor technologies. The 35 W output power is generated using CGHV40030 GaN HEMT which is sufficient to drive further stages of power amplifier. The driver amplifier is designed at 1.3 GHz of center frequency. This amplifier is designed in class AB and 60.5% of PAE is achieved. © 2018, Springer Nature Singapore Pte Ltd.