Research And Design Of Dual-band High-efficiency Microwave Power Amplifiers

The power amplifier(PA)is a key component to realize the radio frequency(RF)and microwave system,and the optimization of their performance has always been the focus in the research of PA.On the one hand,the RF PA is generally the highest power consumption and largest volume module in the communication system,and its performance will directly affect the operating cost of the entire RF system.Highefficiency PAs can reduce costs by reducing power loss and heat dissipation requirements.On the other hand,with the development of modern communication technology,more and more advanced wireless multiband standards have emerged,which requires the communication systems to work on multiple frequencies at the same time.Therefore,the design of multi-band PAs has attracted more and more attention.In this article,the design method for dual-band high-efficiency PA is studied.This article designs and implements a 0.915 GHz and 2.45 GHz dual-band highefficiency PA,this frequency band is often used in industrial,scientific and medical(ISM)fields.All matching networks and bias circuits are implemented by microstrip lines.The main work and innovations of this article mainly include the following three aspects:(1)The traditional single-band complex impedance transformer and dual-band real impedance conversion are theoretically deduced and analyzed,and a dualfrequency complex impedance transformer with only a single stub is proposed.The prototype of operating frequencies 1GHz and 2.5GHz was designed and manufactured to verify the effectiveness of the impedance transformer.The transformer has the characteristics of short overall electrical length and low computational complexity,and can realize the transformation from two different complex impedances to the same real impedance at two unrelated frequencies.Simulation and test results verify the effectiveness of the impedance transformer,which is easy to implement with microstrip lines.(2)A dual-band complex impedance transformer based on a ?-type network is proposed,and the effectiveness of the transformer is verified by simulation and actual measurement results.This structure only uses four sections of transmission lines,which is conducive to the miniaturization of the device.Since the characteristic impedance of the first section of the transmission line can be selected,the impedance transformer has strong flexibility.(3)In this article,a dual-band high-efficiency PA is designed and implemented.The two second harmonic impedances of the power amplifier are well controlled,the design of the input and output matching network is based on the proposed ?-type network of the dual-band complex impedance transformer,and finally achieves good dual-band performance in 0.915 GHz and 2.45 GHz.The maximum output power is greater than 40 d Bm,which suppresses the second harmonics of the two operating frequencies,and improves the power added efficiency(PAE)of the PA.The maximum PAE is 78.8% and 73.12%,respectively.