Investigations On Microwave And Millimeter Wave GaN Power Amplifier MMICs

Microwave and Millimeter wave solid-state power devices are critical components in electronic systems such as wireless communications,navigation and radar.Due to the outstanding properties of GaN,such as wide band-gap(3.40eV),high critical electric-field,high thermal conductivity and high power density,GaN-based microwave and millimeter wave devices have great potential in applying in power Monolithic Microwave Integrated Circuit(MMIC)with excellent performance.The dissertation revolves around the nonlinear model of GaN HEMT,the ultra-broadband,high efficiency,high linearity,and multimode operation of GaN MMIC.The main achievements are as follows:1.GaN HEMT device's nonlinear model.Accurate GaN HEMT device nonlinear models are essential for designing high performance power amplifier MMICs.Here,the non-linear model of 6×50?m GaN HEMT device is extracted based on the improved Angelov-GaN method.Simulated device's DC and AC performance using this model shows good agreement with the measured results.2.Wideband GaN power amplifier.Two kinds of broadband circuit topologies including Reactive Matched Power Amplifier(RMPA)and Distributed Amplifier(DA)are adopted in the design of wideband power amplifier MMICs.6-18GHz(12W)and 26-40GHz(17W)MMICs are designed using RMPA,while the 2-18GHz(10W)MMIC is designed adopting DA as the working frequency(2-18GHz)is beyond three octaves.Deign of thermal and wideband matching network are the key points in the 6-18GHz PA design to ensure high output power and reliability.An output power of 13.8-21.4W and a power added efficiency(PAE)of 21%-35%over the band of 6-18 GHz(Vds=28V,CW)have been achieved.The chip size is 2.6×3.6mm~2 and the thermal resistance is 1.55?/W.It has been widely used in the engineering.26-40GHz 17W GaN-based Balanced PA is designed.A novel design method of optimizing load impedance(40?)of the Lange Coupler is presented to solve the conflict between microwave performance and process design rules.An output power of more than 15.8W and a power added efficiency>15%over the band of 26-40 GHz(Vds=20V,CW).The chip size is 3.5×5.3 mm~2.Finally,the DA method is adopted in 2-18GHz(10 W)PA design,which shows an output power of more than 10W and a PAE>20%(3.5×4.8mm~2).3.High efficiency and high power GaN power amplifiers Two X-band(8.5-10.5GHz60W,8-12GHz 60W)power amplifiers(PAs)and millimeter-wave 33-37GHz 20W PAs were developed.A compact LC resonant structure was adopted in the input of power stage of 8.5-10.5GHz 60W power MMIC to improve the PAE from 45%to 50%.And the chip size is the same as that of a conventional amplifier.The technology of controlling gain compression proposed in the thesis is adopted in the design of 8-12GHz 60W power amplifier MMIC.It achieves the saturated performance(60W,40%)when the gain is compressed at 6dB.The chip has been applied in the engineering.Millimeter wave power amplifier(33-37GHz,20W)has been designed with load-pull method.A method of using the resonant structure to calibrate the capacitance of the process is proposed.At the same time,the pre-matching structure is used to extract the optimum matching impedance of the unit cell,which reduces the error caused by the Load-Pull system.It shows an output power of 43.1-43.5dBm and a high PAE of 30%-34%between 33-37GHz.Compared with the state-of-art Ka-band PA MMICs,this PA achieves good Pout and PAE.4.GaN-based power MMICs used in 5G mobile communication.24-28GHz Doherty power MMIC is development.Simulations result shows a saturated output power of 32dBm with PAE>35%,while the 6dB back-off PAE is larger than 25%in the frequency of 26GHz.In order to realize PA's high linearity such as high IM3,Sweep Spot method is adopted for the24-27GHz PA MMIC design.Measured result shows a saturated output power of 10W and maximum of PAE 25%.The 6dB back-off IM3 and PAE is measured to be higher than 30dBc and 15%.5.X-band dual-mode GaN power MMIC.Dual-mode Amplifier can work in pulse(PL)and continuous wave(CW)condition.High power and efficiency can be provided when PA works in PL mode.As for the CW mode,the PA's power dissipation is lower than the average power consumption with PL mode while the output power can still meet requirement.In order to realize the switching between this two modes,a novel design with a positive-voltage control power switch added in the circuit topology is presented.The fabricated 7-13GHz dual-mode power MMIC shows an output power of more than 25W and PAE of greater than 35%under PL mode.Under the CW mode,it gives an output power of more than 1.58W and PAE greater than 20%.