| With the development of communication technology,new communication standards are constantly being proposed and more and more frequency bands are gradually being used.RF power amplifiers which are an important part of the transmitting front-end in wireless communication systems meet these requirements,the operating bandwidth of power amplifiers require to be increased or dual-band operation requires to be achieved.Meanwhile,high efficiency also needs to be achieved,which the existing approaches are the control of harmonics.Maintaining high efficiency of broadband and dual-band power amplifiers has become the focus of this thesis,so the operating bands of power amplifiers and their efficiency have been extensively studied in depth,with the main research in this thesis is as follows:1)A continuous class F broadband based high efficiency power amplifier is designed.Firstly,the harmonic control principle of continuous class F amplifiers is analysed,combining the harmonic control network of continuous class F with the output matching network.Then,the 3rd order Chebyshev low-pass filter prototype is used as the input matching network.A continuous class F broadband high efficiency power amplifier based on the operating frequency of 1.2 GHz-3.3 GHz is designed.Simulation results show that its relative bandwidth is 93.3%,output power is 40-40.9 d Bm,drain efficiency is 60-63.9%,gain is 10-10.9 d Bm,and the overall index parameters are relatively flat in the 1.2-3.3 GHz operating frequency range.2)A dual-band power amplifier based on Class F–1/F is designed.Firstly,the principle of harmonic control of Class F–1 and Class F amplifiers is analysed.As Class F–1 and Class F are different for harmonic modes,the differences are reflected by the position of the harmonic impedance in the Smith circle diagram.The former requires the second harmonic point to be at the short circuit point and the third harmonic point to be at the open circuit point,while the latter requires the second harmonic to be at the open circuit point and the third harmonic to be at the short circuit point.To meet these requirements,the choice of operating frequency point is particularly important.Secondly,the harmonic control methods of class F and F–1 are applied in the bias circuit.Then,the dual frequency matching network is analysed and investigated.Simulation results show that the output power is 40.5-40.8 d Bm and 39-39.5 d Bm,the gain is 11.5-11.8 d B and 10-10.5 d B,and the drain efficiency is 68-75%and 60-66.2%in the frequency range of 2.3-2.5 GHz and 4.9-5.1 GHz.It was processed and the test results were different from the simulation results,with output power of 38-39.4 d Bm and 37-37.7 d Bm,gain of 9-10.4 d B and 8-8.7 d B,and drain efficiency of 62-70%and 55-58%in the frequency range of 2.3-2.5 GHz and 4.9-5.1 GHz.Finally,the reasons for the difference between the test and simulation results are summarised.3)A dual band Doherty amplifier based on Class F–1/F is designed.Based on the study of class F–1/F based dual-band amplifiers,the relevant principles have been applied to Doherty amplifiers and dual-band Doherty amplifiers operating at 2.4 GHz and 5 GHz based on class F–1/F have been designed.The simulation results show that the saturated output power is 39 d Bm and 38.2 d Bm,and the saturated drain efficiency is 64.2%and 71.8%,when the gain is 10 d B and 9.2 d B,and 6 d B backoff efficiency is 40%and 35%at 2.4 GHz and 5 GHz. |
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