Research On The Model Of GaN HEMT Device And High Efficiency Power Amplifier

Microwave power amplifier is the core device of all wireless communication systems.With the miniaturization of communication system,reliability and other needs to further improve,high efficiency power amplifier has become a bottleneck of new generation wireless communication systems.In recent years,gallium nitride?GaN?high electron mobility transistor?HEMT?is a research hot of solid-state power device in domestic and foreign for high frequency,high power,high efficiency,high temperature and other advantages.Large signal device model is the premise of circuit optimization design.It is of great significance in optimizing the device structure and improving the performance of power amplifier circuit.Therefore,based the model,this paper aims at the research on high efficiency power amplifier design theory and methods.The main contents include:1.Theoretical study on class E power amplifier with pi network.Aiming at the output parasitic inductance of the microwave GaN HEMT device,which leads to the maximum operating frequency and bandwidth of the traditional E class power amplifier to be limited,the topology of the Class E power amplifier with pi network is proposed.The analytical expressions of current and voltage are deduced.The waveforms for the maximum load,maximum operating frequency,parallel resonance and second harmonic parallel resonance are given.The maximum values of the current and voltage in a broadband range and the output power capability are derived.The analytical formula of the normalized component value of the load network of the class E power amplifier with pi network is obtained.The results show that the class E power amplifier with pi network has the advantages of flexible design and high output power capability compared with other topologies,and provides a manner to improve the performance of the power amplifier.2.Research on broadband class E power amplifier with pi network.The influences of the output parasitic inductance on the load resistance,the series reactance,the maximum operating frequency and the initial phase are studied for the design of the class E power amplifier with pi network.The analysis results show that optimizing the output series inductance can increase the bandwidth of the load network.The variation behaviors of the conductance,susceptance and phase angle of the load are analyzed.The broadband class E power amplifier with pi network is designed and fabricated using the microwave HEMT large-signal equivalent circuit model at 2.5?3.5GHz?33.3% fractional band width?.The efficiency is 60%⁶9%,the output power is greater than 35.2dBm.It possesses a wide range of operating frequency and has a high efficiency at high-frequency for broadband operation,which verifies the correctness of the theoretical analysis and design.3.Research on wideband EF₃ power amplifier with pi network.To further improve the efficiency,on the basis of the broadband characteristics of Class E power amplifier with pi type network,the class EF₃ power amplifier with pi type network is proposed by taking advantage of the high efficiency of class EF power amplifier.In the load network,the switching voltage satisfies the zero voltage condition and the zero voltage derivative condition,the second harmonic is short circuit,the third harmonic is open circuit,and the harmonics is suppressed to improve the efficiency.Based on the self-built GaN HEMT scalable large-signal model,the broadband class EF₃ power amplifier with pi-type network in S-band is designed and fabricated at 2.9?4.0 GHz?31.8% relative bandwidth?.The efficiency is 67%?77.9% and the gain is more than 7.16 dB,and the output power is greater than 37.4dBm.The high-efficiency amplifier in S-band is realized,which verifies the correctness of the circuit theory and design method.4.Design of high power and high efficiency MMIC power amplifier at C band based on large-signal statistical model.The discreteness of GaN HEMT is larger,while the traditional model is built on a single device.It cannot describe the characteristics of multiple devices accurately,so the accuracy of the circuit design is insufficient.In this paper,a circuit design method based on large-signal statistical model is proposed.Based on the harmonic control theory,a three-stage MMIC power amplifier is designed in the 5.0⁶.0GHz?18.18% relative bandwidth?.Harmonic control is used at the last level of power amplifier.The PAE is greater than 45%,the gain is greater than 26 dB,and the output power is greater than 49 dBm.The device power efficiency is effectively improved and is the highest so far to our knowledge,which verifies the correctness of the circuit design and statistical model.