Research On High Efficiency RF Power Amplifier Based On Novel Power Combiner

The high-speed development trend of modern communication technology puts forward higher requirements for the broadband and high-efficiency performance of RF power amplifier.As the most energy consuming module in the communication system,the efficiency improvement of power amplifier not only means that it can reduce the heat loss,greatly reduce the cost of heat dissipation,but also improve the output power,so as to improve the overall performance of the transmitter.In this thesis,the efficiency improvement technology of two-way power amplifier system is studied,and two high-efficiency two-way power amplifier systems are designed,which are Doherty power amplifier and outphasing power amplifier.In this thesis,first of all,the literature review work in related fields is carried out,and the research status of various power amplifier efficiency improvement technologies,the current research status of Doherty power amplifier and outphasing power amplifier domestic and aboard are introduced.Meanwhile,their basic circuit structure and principle are analyzed and elaborated.In view of the shortcomings of load modulation network in the traditional Doherty architecture,a novel design of load modulation network based on post matching technology is proposed.After the software simulation design and circuit processing,the measurement of the circuit is completed.The circuit uses the Cree's Ga N CGH40010 HEMT.According to the results of large signal measurement,the improved Doherty power amplifier in the frequency range of 3.2～3.7GHz,the drain efficiency is above 60%,the maximum drain efficiency is 72.5%,and the peak output power is about 43 d Bm,while gain is more than 10 d B.With an output power back-off 6d B,the drain efficiency is above 40% and the maximum drain efficiency is 48.5%.Basically consistent with the simulation results.Based on the experience of the improvement of Doherty power amplifier's combiner structure,and the analysis of the power combiner in the traditional outphasing architecture,the defects of the power combiner are improved.Using the principle of load compensation network,the whole simulation design of outphasing power amplifier system is carried out by using offset transmission line instead of compensation reactance and combining with broadband high efficiency class F power amplifier.The simulation results show that the output power is higher than 43 d Bm,the average drain efficiency is higher than 65%,the maximum drain efficiency is 73.4% in the frequency band of 2.6～3.6GHz.With an output power back-off 7d B,the drain efficiency is above35% and the maximum drain efficiency is 45.2%.In summary,the power amplifier designed in this thesis basically meets the predetermined design specifications.The efficiency and bandwidth performance of the two power amplifiers are improved to some extent through the efficiency improvement technology proposed.