Research And Design Of Dual-Band High-Efficiency RF Power Amplifiers

The radio frequency(RF)power amplifier(PA)is one of the most important energy-consuming component of the modern mobile communication systems,and the efficiency level of the RF PA directly determines the power consumption,heat dissipation and circuit size of the RF front-end.Recently,various efficiency improvement strategies of RF PA have been proposed,such as the class-E switch-mode PA and the class-F/class-F^-1harmonic-tuned PA.However,the parasitic effects of the packaged transistor under RF/microwave have serious impact on the optimal impedance matching of the PA,which degrade the efficiency performance of the PA.Moreover,in order to meet the development of wireless communication technology to multi-mode/multi-band operation,the research of high-efficiency dual-band(DB)PA has attracted more and more attentions.However,the increase of the operating frequency band of PA also bring certain challenges to the design of DB impedance matching circuits.Therefore,based on these two hot issues,this paper starts from the research of high-efficiency RF PA,and further explores the efficiency improvement method of DB PA.Hence,the main contents of this paper includes the following two aspects:1.In terms of the high-efficiency PAs:due to the parasitic parameters of packaged transistors restrict the maximum operating frequency(f_max)of class-E PA and the matching accuracy of the output matching circuit of class-F/class-F^-1PA.Two kinds of output matching circuits are proposed for the class-E PA and the class-F/class-F^-1PA,respectively.The proposed circuits can compensate the parasitics of the transistors at fundamental and harmonics accurately,and have the compact circuit structures.To verifies the feasibility of the proposed method,a class-E PA operating at 2.6 GHz is fabricated and achieves the peak power added efficiency(PAE)of 77%.The class-F and class-F^-1PA operating at 2.4 GHz are fabricated,and the measured peak PAE of them are 75.5%and 77.6%respectively.2.In terms of the high-efficiency DB PAs:under the premise of the above research,aiming at the problem that the traditional DB class-E PA had a complicated output matching circuit due to the compensation of the excess output capacitances of the transistor.A novel method is proposed in this paper for designing the DB class-E PA.The excess output capacitances at the two desired frequencies can be compensated using the proposed output matching circuit without separate design of harmonic compensation circuit,thus the fundamental and harmonic impedances for DB optimum class-E operation are achieved above the f_max,considering the parasitics of the packaged transistor.Based on the proposed method,the fabricated DB class-E PA features the peak PAE of 74.1%and 72.6%at 1.9 GHz and 2.5 GHz respectively,and the efficiency performances of the DB class-E PA are improved.