Design of radio frequency high power linear and harmonically tuned amplifiers

With the continuous development of modern wireless communication systems, demand for cost effective, highly efficient and compact systems is increasing. Among all the components in the communication system, the RF Power Amplifier (RFPA) is the critical component, because of its great impact on the overall system performance in terms of linearity, efficiency and bandwidth. The performance of RFPA is mainly determined by the active transistor present in it. The advancements in the semiconductor device technologies has resulted in the development of GaN RF power transistors, which has been proven to be effective for high power and high frequency applications. The main objective of this thesis is to design high frequency linear radio power amplifiers (class AB) and the harmonically tuned class-J RF power amplifier using the commercially available GaN-on-SiC HEMT and GaN-on-Si HEMT devices. The detailed description of the matching networks design, fabrication of the amplifiers and the measurement procedure are also presented. Two different linear power amplifiers are fabricated using GaN-on-SiC HEMT and GaN-on-Si HEMT devices. Results obtained from linear class AB RF amplifier using GaN-on-SiC HEMT demonstrated a power added efficiency (PAE) of 68% and drain efficiency of 77%, which is one of the highest PAE reported at 3GHz. This thesis also describes the design methodology of harmonically tuned class J RF power amplifiers using the GaN-on-SiC HEMT. Two different types of matching network topologies are adopted for the design. The descriptions of the matching network topologies, matching network designs, amplifiers fabrication and the experimental results are also presented.