Study On 1MHz-40GHz Ultra Wideband Distributed Low Noise Amplifier

As an important component of receiver,ultra-wideband low noise amplifier has important applications in military radar,optical communication,5G communication and measuring instruments.In order to meet the broadband requirements of low-noise amplifiers in broadband systems,this paper analyzes and studies distributed amplifiers to design ultra-wideband low-noise amplifiers that meet the index requirements.The main results are as follows:(1)According to the basic theory of distributed amplifier,a uniform distributed low noise amplifier is designed based on 0.1 5?m GaAs pHEMT technology.ADS software is used for schematic diagram design and layout simulation.The results show that the circuit has a gain of 16.8dB,a gain flatness of 1dB,an input port reflection coefficient S11 of less than-7.6dB,an output port reflection coefficient S22 of less than-6.5dB,a noise coefficient NF of less than 5.1dB,and a stability coefficient of greater than 1 in 1MHz-100GHz.(2)In order to further improve the noise performance of the uniform distributed low noise amplifier at high frequencies,a graded distributed structure is adopted.The gate width of the transistor is reduced step by step by a reduction factor Km,the gate transmission line microstrip line Lg is reduced step by step by a reduction factor Kg,and the drain transmission line microstrip line Ld is amplified step by step by a reduction factor Kd.Schematic design and layout simulation are carried out in ADS software.The results show that the circuit has a gain of 14.1 6dB,a gain flatness of 0.87dB,an input port reflection coefficient S11 of less than-6.5dB.an output port reflection coefficient S22 of less than-9.7dB,and a noise coefficient of less than 3.9dB in the 1MHz-40GHz frequency band.(3)The two circuits are packaged and tested by vector network analyzer and power meter.The test results show that the uniform distributed amplifier has a gain of 16.59dB-12.12dB,a gain flatness of+-±2.235dB,an input reflection coefficient of less than-6.77 dB,an output reflection coefficient of less than-4.2dB,a noise coefficient of less than 4.49dB in a bandwidth of 0.5GHz-40GHz.and a chip area of 1.79*1.075 mm2 in the frequency range of 10MHz-40 GHz.The graded distributed amplifier has a gain of 17.01dB-13.05dB,a gain flatness of 1.98dB.an input reflection coefficient of less than-6.23dB,an output reflection coefficient of less than-4.9 dB,a noise coefficient of less than 3.53dB in a bandwidth of 0.5GHz-40GHz,and a chip area of 1.79*0.79 mm2 in a frequency range of 10MHz-40GHz.Comparing the measured results of the two circuits,it can be seen that the gradient distributed amplifier can improve the noise figure at high frequency and the gain flatness of the circuit.