高性能低噪声放大器的设计

低噪声放大器（LNA，Low Noise Amplifier）能有效放大射频小信号，降低系统的总体噪声，提高接收机的灵敏度。该文介绍了低噪声放大器的主要性能指标和设计方法，该电路选用ATF-54143晶体管，采用两级放大，利用Agilent ADS软件完成一个S波段低噪声放大器的偏置电路以及输入、级间和输m匹配的设计和仿真。本设计中，在源极加入短路微带线形成反馈作用，从而提高稳定性。最后对仿真完的电路进行了加丁测试。经测试，在2.15-2.65GHz的频带内，获得了27-2-28.1dB的增益，增益平坦度小于±0.9dB，噪声系数小于ldB，输入电压驻波比为l.048-1.640，输出电压驻波比为1.120-1.840，在中心频率点2．4GHz上．输出功率ldB压缩点为162dBm。

Design of a High-performance Low Noise Amplifier in S Wave Band

Low noise amplifier can effectively amplify the small RF （radio frequency） signal,lower the noise of the whole system,and increase the sensitivity of the receiver.In this paper,the main performance index- es and design methods of the LNA are introduced.The circuit is made up of two stages with ATF-54143, the biasing circuit,input stage,middle stage and output stage matching circuits of a S-band amplifier are designed and simulated by the software Agilent ADS.In this design,short microstrip lines are added to the source tone to improve the stability of the circuit by their feedback effect.At last,the designed circuit is fabricated and measured.It is showed that,from 2.15 to 2.65GHz,the gain is between 27.2 and 28.1dB, whose flatness is less than ± 0.9dB,noise figure is less than 1riB,input VSWR and output VSWR are 1.048 - 1 .640 and 1.120 - 1.840 respectively.In the center frequency,the output ldB compression point is 16.2dBm.