The Design Of Broadband Power Amplifier And Doherty Power Amplifier

The RF power amplifier is the key component of the radio frequency front end and is also the most power-consuming device in the radio frequency front end.Inefficient power amplifier will waste energy,and generate heat severely,which decrease the performance of radio frequency front end.In addition,with the development of wireless communication technology,communication signal's modulation method is becoming more complex,and the bandwidth of signal is wider and wider,and the PAPR of the signal is higher and higher.Therefore,in the radio front end,the amplifier needs to have broad bandwidth,high peak efficiency and high back-off efficiency.Doherty is the most common used efficiency promotion technology in wireless communication devices due to its easy hardware circuit implementation.Based on the above background,this thesis studies the broadband power amplifier and Doherty power amplifier and has done the following works:1.In response to the problem of high-efficiency single-ended power amplifier have difficulty working over octave band,the resistive-resistive continuous inverse F theory is used to design a broadband high efficency power amplifier which works at 0.6?2.7GHz(over two octave band).First introduce the resistive-resistive continuous inverse F mode theory,and then design the input matching network of the power amplifier based on low-pass filter method,and the output matching network of the amplifier is designed based on broadband reactive compensation network and broadband impedance transformation network.Finally,the performances of power amplifier were measured as follow:saturation power is 39?41.7 d Bm,PAE is 48.6%?61.4%,saturated gain is 9.4 to 11.8 d B from 0.6 to 2.7 GHz.2.For scenarios where the peak-to-average ratio of 5G communication signals is greater than 6d B,A high efficiency asymmetric Doherty power amplifier working at 3.5 GHz is designed.By analysing the function of phase offset line in carrier amplifier and peak amplifier,establish the design method of the phase shift line.The meseaured performances of power amplifier are as follow:peak output power is 43.5d Bm and PAE is 56%,the PAE at 8d B backoff is 42%.3.Propose a new design method of dual-band Doherty power amplifier.By performing susceptance compensation on the basis of a relative narrowband Doherty structure,the effective frequency range of the structure is broadend and the backoff efficiency of the structure is improved.Dual-band Doherty power amplifier is achieved by selecting two frequency to perform susceptance compensation based on this structure.According to this method,a dual-band Doherty power amplifier which works at 2.6/3.5GHz is designed,the measured result shows that at 2.6GHz,the peak output power is 42 d Bm and PAE is 45.4%,the PAE at 6.2d B backoff is 45.8%.At 3.5GHz,the peak output power is 42.5d Bm and PAE is 56.7%,the PAE at 6d B backoff is 43.7%.