Research And Design Of RF Power Amplifier For New Generation Mobile Communication

To improve coverage and communication quality of base stations,a large number of base stations at different levels need to be deployed,and the new 5G standard also poses new challenges to the linearity and efficiency of RF power amplifiers.5G broadband performance tends to cause the linearity deterioration of RF power amplifiers,and various linearization techniques are the key to the research.Higher carrier frequency will lead to greater space loss,and the base station distribution density is larger.On the premise of maintaining the linearity of the power amplifier,energy consumption should be reduced as much as possible to maintain the sustainable development of 5G.The efficiency improvement of a RADIO frequency power amplifier is a hot research spot in the future.This paper first introduces the basic theory of RF power amplifiers,covering scattering parameters,stability,matching principle,and power amplifier classification.Then,it analyzes the nonlinear distortion of power amplifier,and introduces several linearization techniques.After that,it introduces the device theory of the process used in this design,covering working principle and characteristics,active device model,and passive device model.Then,the design theory of RF power amplifier combined with the simulation characteristics of HBT device is used to determine the circuit architecture,and an adaptive linearized bias circuit with temperature compensation is designed by using the thermoelectric effect of transistors and transconductance changes under high power input.Then the circuit level simulation software is used to determine the matching circuit,the load line matching and equal Q value theory is used to determine the output matching network.The output transistor collector in parallel to the ground series resonance network effectively suppresses the bias in class AB second harmonic distortion.The output matching circuit also uses SMD components to facilitate subsequent tuning.A parallel RC negative feedback branch is used in the first and second circuits to ensure the stability of the whole circuit and improve the design of the input matching.Finally,the DC characteristics,stability,and RF performance are verified by electromagnetic simulation optimization several times.The RF power amplifier working in the 5G N79 band(4800 MHz-5000 MHz)was developed.The gain was 31 d B,the saturation output power was 33 d Bm.When the output was at 24.5 d Bm,the adjacent channel suppression ratio was-45.9 d Bc;while the second harmonic suppression ratio was-59.8 d Bc and the power added efficiency was 13%.The test results show that the design of the power amplifier performance is good which is in line with the expected index.In addition,to meet the high power application of 5G,a power synthesis circuit is simulated and designed.The simulation results show that its saturation output power reached at 36.5 d Bm.