Research And Design Of Microwave Broadband Low Noise Amplifier

In recent years,wireless communication has been widely applied to aerospace,military,mobile communications,and Internet of Things.With the advent of the 5G era,its application fields will be further extended.The wireless communication industry will move toward higher frequency,higher transmission rates,wider coverage and stronger compatibility.These make higher requirements for wireless communication devices.One of the key points is to expand the bandwidth of the device.It could meet the compatibility of the device with different communication standards and satisfy the demands of different application scenarios,so it has great advantages in terms of equipment cost,power consumption and volume.As one of the key modules of the receiver,the low noise amplifier determines the overall performance of the receiver.Therefore,microwave broadband low noise amplifier has become a hotspot in academic and industrial research,and it possess broad application prospects and market value.This thesis focuses on the topic of broadband amplifiers,mainly expounding the following:First of all,we have investigated and summarized the domestic and foreign literatures related to microwave broadband low noise amplifiers in recent years,then briefly explained the basic theory and key indicators of low noise amplifiers,and introduced the classification of noise.Then,the amplifier's broadband technology was studied and summarized.Finally,three low noise amplifiers were designed and their design process was analyzed in detail.Based on the application of Sub-GHz,two wideband low noise amplifiers were designed based on GaAs pHEMT process.The first low noise amplifier utilizes Cascode structure to achieve high gain and high isolation,and uses RC negative feedback to achieve wideband input and output matching.The test results show that the power gain is 19dB±0.25 dB,the input and output return loss is less than-15 dB,the output P-1dB is above 23 dBm in 20MHz-1GHz,and the noise figure is less than 1dB(simulation result).The second low-noise amplifier also uses the RC negative feedback structure to achieve broadband characteristics.The Darlington structure composed of the enhancement transistor and the depletion transistor further expands the bandwidth while achieving the circuit self-bias.The test results show that the amplifier achieves 16 dB gain and 22 dBm output P-1dB,input and output return loss is less than-10 dB,and the noise figure is 1dB(simulation result).For the millimeter wave application,this paper designed a broadband low noise amplifier covering the K and Ka bands based on the GaAs pHEMT process.The circuit utilizes a four-stage common-source cascade structure combined with a multi-elements filter matching structure and a series-parallel inductor peaking technique to achieve better gain and output P-1dB in the wideband range.The test results show that the LNA achieve 20 dB power gain,the output P-1dB reaches 22 dBm,and the input and output return loss is less than-10 dB in 18-40 GHz.