Research On Broadband GaN MMIC Power Amplifiers For 5G Communication

With the rapid development of the fifth generation mobile communication technology(5G),human society has put forward higher performance requirements to the core components of RF/microwave front-end circuits—power amplifiers,including broadband,high-efficiency and miniaturization.Microwave monolithic integrated circuits(MMIC)based on GaN technology have the natural advantages of high power density,wide bandwidth and high-efficiency,which can meet the needs of 5G communication for the high-performance power amplifiers.Therefore,the thesis will focus on the research of GaN MMIC power amplifier for 5G communication,and the contents of this thesis are concluded as follows:1.In 5G communication application scenarios,in order to ensure the coverage and overall size of small cellular base stations,the output power density of the power amplifier needs to meet some requirements.In this thesis,a basic theoretical analysis of the topology structure—Stacked-FET structure which can increase the output power of the power amplifier is carried out.It is found that the Stacked-FET structure has a higher single-stage output power,a relatively larger equivalent optimal impedance and is easier to achieve the out match network than the structure of the parallel transistor which the other way to increase the output power.Therefore,this thesis proposes a scheme to design the corresponding GaN MMIC power amplifier based on the StackedFET structure.Before designing two MMIC power amplifiers,a Stacked-FET structure is adopted,and the Cree CGH40010 package transistor is used to verify the feasibility of the corresponding design scheme.A power amplifier operating at 1.6-2.8 GHz is designed and the simulation results show that its saturated output power is between 42.7-43.3 dBm,the saturated power-added-efficiency(PAE)is 54.4%-57.6%,and the saturated power gain is 14.7-15.3 dB.2.The high-efficiency power amplifiers have a rich out-of-band spectral component,which will interferes with signals from other channels outside the band.Therefore,it is necessary to cascade a filter with harmonic suppression function at the end of the high-efficiency power amplifier.However,if the power amplifier and the harmonic filter are designed independently,and then simply cascade together,the harmonic power reflected by the harmonic filter will inevitably affect the matching performance of the original power amplifier.Therefore,when designing a highefficiency power amplifier's output matching network,the harmonic suppression effect of the matching network is considered in this thesis and the Cree CGH40010 package transistors are used to design a power amplifier with harmonic suppression filter structure.The measured results show that the saturated output power in the 1.7-2.6 GHz band is better than 41 dBm,the saturated gain is greater than 13 dB,the saturated PAE is 53.3%-69.8%,and the suppression ratio of the second and third harmonic power related to fundamental power is better than-40 dBc.3.In 5G communication application scenarios,the signal has the characteristics of large bandwidth.In this thesis,the continuous mode power amplifier is used to achieve the broadband and high-efficiency of the power amplifier.The topology is combined with the Stacked-FET structure and two parallel power synthesis to improve the output power density of the MMIC,and to meet the requirements of small cellular base stations' coverage and miniaturization.Finally,using the OMMIC 100 nm GaN process on Si substrates,a MMIC power amplifier working in the 1.8-4 GHz frequency band is designed.In the case of 20 V drain bias voltage and 20 dBm input continuous wave signal,the saturated output power is 35.2-35.6 dBm,the saturated gain is 15.2-15.6 dB,the saturated PAE is 49.9%-58.4%,and the entire chip area is 1.6 mm×3.8 mm.4.In the 5G communication application scenario,the modulated signal has the characteristic of high peak-to-average ratio.In this thesis,the symmetric Doherty architecture is used to improve the back-off efficiency of the power amplifiers,and the Stacked-FET structure is used as a single output power unit to increase the output impedance,make it easier to design output matching network.So it can remove the post-matching circuits and save chip area.Finally,using a research institute's 0.25 ?m GaN process on SiC substrates,a Doherty MMIC power amplifier operating in the 3.2-3.8 GHz frequency band is designed.Its simulation results show that its saturated output power is higher than 40 dBm,saturated PAE is 36.8%-45.6%,6 dB back-off PAE is 23.1%-29.8%,saturation gain is 16.1-18.1 dB,and the entire chip area is 3.5 mm×2.4 mm.