DESIGN, ANALYSIS AND DEVELOPMENT OF GAN BASED CONCURRENT DUAL-BAND DOHERTY POWER AMPLIFIER

Abstract

A dual-band power amplifier has been designed to operate in 2.4-2.48 GHz and 5.15-5.35 GHz. Doherty configuration is used, so as to obtain better linearity and efficiency. In this configuration, two power amplifiers are used in parallel. The bias points of the active device are found out, for both, class A and class AB operation. Bias circuits, designed to operate at both the bands, have been designed using T-type microstrip lines. Load pull/ source pull simulations are done for both amplifiers to figure out suitable input and output matching networks to put the device in the stable region. Matching networks, to match complex frequency dependent impedances, at both frequency bands, are designed using 4-section stepped impedance resonators for both amplifiers. Dual-band power splitter and combiner are also designed. All the above parts were designed and simulated, both in schematic and layout. Finally, all parts have been integrated to make the complete circuit. Simulations are done to obtain various parameters of Doherty Power Amplifier. Finally, the Doherty power amplifier has been fabricated and various measurements have been done.