Highly Integrated Wideband Doherty Power Amplifier

Sammanfattning: The objective of this thesis project was to design a wide band Doherty Power Amplifier (DPA) using bare die transistors. Different techniques had been applied in this thesis to make a DPA wide band while maintaining its efficiency and power. The study of a phase shifter and combiner network was made to find a solution to achieve the desired bandwidth. To determine the best suitable class of amplifier for DPA design, three different classes A, B, AB were considered. The symmetric AB class was used for the main and peak amplifiers. A 15 W GaN HEMT transistor was used for both main and peak amplifiers. The desired range of frequency is from 2 GHz to 3 GHz having 46 dBm peak power with 60% efficiency and 55% efficiency at 6 dBm back off. For the combiner, network Roger’s RO4350, Arlon’s AD1000 and STMicroelectronics’ glass substrate with copper fabricated on it was used. The size of the combiner was 3 mm x 8 mm for AD1000 and 0.7 mm x 0.9 mm for glass substrate. The phase shifter was designed using GaAs technology. The thesis work was validated using ADS Design Tool v2011 and v2009 using design kits for GaAs and glass substrate. Multiple design configurations were simulated, and the design supporting high efficiency and good bandwidth was considered. The band achieved was 2 GHz to 3 GHz with an average efficiency of 58% at 46 dBm peak power and 51% average efficiency at back off power of 40 dBm using the three different substrates. The designed DPA can be used for multiple wireless communication systems such as LTE and WCDMA.