Research On Monolithic Broadband Amplifier Based On GaAs/GaN Process

The MMIC circuit has been applied in many fields such as phased array radar,instrumentation,satellite communications and fiber optic systems due to the advantages of small size,light weight and high reliability.Low noise amplifiers and power amplifiers are key components in RF front-end circuit.With the rapid development of wireless communication technology,broadband MMIC amplifiers have more and more requirement.Therefore,the research on broadband MMIC amplifiers is of great significance.First,a comparative analysis of common broadband amplifiers is proposed.Then,based on the 0.15?m GaAs pHEMT process,a wideband low noise amplifier circuit operating from 2 to 6GHz is designed.The complete circuit contains a two-stage cascaded amplification structure.The feeding circuit of the low noise amplifier adopts single power supply,which simplifies the topology,In order to compromise the noise matching and input matching,an inductor is connected to transistor source in the first stage.The two-stage circuit of the low noise amplifier adopts parallel negative feedback technology,thereby expands the operating bandwidth.This article analyzes the design method of circuit schematic and layout of MMIC low noise amplifier.The layout simulation results show that the noise figure is less than 1.6dB,the gain is 19?19.4dB,the input end reflection coefficient S11 is less than-12.8dB,and the output end reflection coefficient S22 is less than-8.3dB in the working bandwidth from 2 to 6GHz.GaN HEMT has many essential advantages such as greater output power and higher operating efficiency.In this thesis,a wideband MMIC power amplifier is designed by using 0.25?m GaN HEMT process.The output matching network is the key circuit in the amplifier.Reactance matching network is used to design the output stage,and the output matching network is determined by combining the trend of impedance curves on the Smith chart.The layout simulation results show that the output power of the MMIC power amplifier is greater than 38dBm,the power-added efficiency is 29%?48.8%,the input end reflection coefficient S11 is less than-7.7dB,and the output end reflection coefficient S22 is less than-9.2dB in the operating bandwidth range of 2-4GHz.