| With the vigorous development of communication technology nowadays,the distribution of communication frequency bands presents a trend of fragmentation.As an important part of the RF transceiver system,power amplifiers should have multi communication frequency band working compatibility to meet the needs of highcapacity communication.With the increase of power amplifier applications,the traditional single mode power amplifier can no longer meet the needs of modern society.At the same time,due to the advantages of higher gain,efficiency,and operating frequency of RF transistors developed in combination with third-generation semiconductor materials,the research on dual band power amplifiers with multiple operating standards,multiple frequency bands,and broadband high-efficiency Doherty power amplifiers(DPA)also has more practical value.This thesis mainly focuses on the following two aspects of research and design:1.Aiming at the limitations of solving dual frequency impedance matching networks nowadays and the problem that the gap between their working low frequency points and high frequency points is often insufficient for a frequency doubling of the low frequency.A simple structure and convenient solution based on type-л the strict theoretical analysis and simulation optimization process are given for the dual frequency impedance converter.The dual frequency impedance converter designed can achieve matching between two independent complex impedances to real impedances at any frequency.Based on this,a parallel dual frequency high efficiency power amplifier is designed and fabricated.The joint simulation results show that the designed power amplifier has a saturated output power of 41.53 d Bm and 40.75 d Bm in the0.61 GHz and 2.6GHz frequency bands,with gains greater than 11 dB.The power added efficiency at saturated output is 68.3% and 56.3%,respectively.2.Aiming at the bandwidth limitation problem of traditional Doherty power amplifiers,a 3.4～3.6GHz broadband high-efficiency Doherty power amplifier is designed.The output matching network designed based on dual impedance matching technology can simultaneously meet the saturation power load impedance of DPA and the impedance matching between load impedance and load during rollback,simplifying the load modulation network.The post matching structure replaces the 1/4 wavelength impedance inverter in the load modulation network to reduce the bandwidth limitation effect of the 1/4 wavelength line.The joint simulation results show that within the operating frequency band,the DPA has a saturated output power of 44 d Bm(25W),a power additional efficiency of 61% at saturated output,a power backoff efficiency of6 d B,and a power backoff efficiency of 8dB,respectively,reaching 50% and 40%. |
