Design Of Low Noise Amplifier And RF Receiving Front End For 5G Base Station

With the development of 5G communication technology,the data transmission rate is increasing,which poses new challenges to the RF receiving front-end.As an important part of the base station's RP front-end,the gain,noise,linearity and other indicators of low noise amplifier directly affect the performance of the entire receiving link.In this paper,a LNA chip based on 0.25 μm GaAs E-pHEMT technology is studied and designed,and the RF receiving FEM is composed of this LNA and a single-pole double-throw switch.This paper analyzes several common LNA structures and proposes a two-stage structure based on current reusing technology.In order to make the LNA more practical,a control circuit is designed to turn off the LNA,and an ESD protection circuit is designed to improve the electrostatic protection level of the LNA.According to the actual demand,the LNA and the SPDT form a module,and the evaluation board is designed to test the performance of single LNA and module respectively.After testing,the operational band of the LNA is 0.6-4.2 GHz,covering multiple bands including 5G.In the operational band,the gain of LNA is greater than 23dB,the NF is less than ldB,the switching time is about 30ns,the ESD protection level is more than HBM-500V,and the chip size after packaging is 2mm*2mm.The LNA only needs a positive voltage supply,no external matching circuit is needed.Active bias circuit is used inside,which can work in a wide range of voltage from+3V to+5V.The bias current can be adjusted by changing bias resistance,and the linearity of LNA can be adjusted for different circumstances.The LNA can be controlled with 1.8V TTL logic level,and has strong anti-interference ability.By real-time switching off the receiving channel,the LNA can be applied to 5G TDD mode.In the receiving mode of switch and LNA module,the gain is about 22 dB,and the noise figure is about 1.5dB at 3.5GHz.The transmitter branch can withstand 37.5 dBm average power under 8dB PAPR signal.The size of the module is 5mm × 5mm after packaging.The switch and LNA module only needs single positive power supply,and the control voltage of the switch transceiver branch is compatible with 1.8V TTL.It has the characteristics of high isolation,low insertion loss and high power withstanding.It has certain application value in the base station RF front-end.