| With the growing demand for high-traffic mobile broadband service,large-scale Internet of Things technology and industrial automation equipment,the future wireless communication system requires faster data transmission speed,greater data capacity and lower signal delay,which also puts forward higher requirements for the performance index of wireless RF transmitters.As an indispensable component of the RF transmitter end,the power amplifier is the most power-consumed module in the entire transmitter.Its efficiency factor can largely limit the whole RF transmitter's performance and battery life.So how to improve the efficiency factor of the power amplifier has great research significance.Compared to traditional Si and Ge-based CMOS devices,GaAs pHEMT transistors have better frequency response characteristics,power-loss factor,power density and breakdown voltage,which make GaAs pHEMT based amplifiers have higher output power and power added efficiency.Therefore,GaAs pHEMT transistors are an excellent choice for RF high efficiency power amplifiers.Based on the above background,this paper establishes the small signal and large signal models of GaAs pHEMT devices,and designs a class F high-efficiency power amplifier using the the established large signal model.This paper mainly carried out the following work:1.21-component small signal model of GaAs pHEMT device.The physical meaning of the parameters of the small signal model is analyzed,and the model parameters are extracted by using inverse cut-off method and the ratio relation of device gate width,etc.A traditional 16-component small signal model based on GaAs pHEMT is established.For the regret that S12 and S21 of 16-component small signal model do not fit well at high frequency,this paper adds charging resistor Rgd characterizing the ohmic forward bias effect,resistor Rfs simulating the effect of the gate-source conduction current and gate finger capacitances describing the multi-gate finger effect of the device on the basis of the traditional model,which successfully improves the fitting precision of the S-parameter of the small signal model of GaAs pHEMT device,so that the fitting error in the frequency range of 2~50GHz is less than 6%.2.Temperature dependence of EEHEMT large signal model of GaAs pHEMT device.Based on the small signal model,EEHEMT large signal model is established by extracting Schottky diode parameters,transconductance parameters,drain-source current parameters and charge parameters of GaAs pHEMT devices respectively with the help of S parameter test data under multi-bias points.In addition,by modified the self-heating effect parameter Peff in the EEHEMT model,the shortcomings of using the built-in temperature parameters of the EEHEMT model to accurately characterize the high temperature characteristics of the device are overcome,so that the DC,S-parameter and power characteristics are good at 25°C and85°C,which improves the prediction accuracy of the model in the power amplifier design.3.Class F high efficiency MMIC amplifier using harmonic control method.The negative effects of current source plane and transistor non-ideal factors on the circuit design are analyzed,and a design method of class F amplifier that uses harmonic control theory to extend the matching circuit design space is proposed.A harmonic matching circuit based on multistage LC structure is proposed,which overcomes the disadvantage of traditional matching structures that are difficult to realize high-order harmonic matching,and achieves a good matching of fundamental and high-order harmonics of class F amplifiers.Combining the above method with the temperature dependence of EEHEMT large signal model,a class F high efficiency MMIC amplifier is designed.The layout simulation results show that,the PAE of the amplifier reaches a maximum of 62.4% at 10 GHz,the corresponding output power is 22.85 dBm,and the power gain is 7.85 dB.In addition the 3dB bandwidth of the amplifier output power reaches 7.2GHz,and the PAE exceeds 50% in the frequency range of 7.9~11.2GHz. |
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