Research On GaAs Wideband Monolithic Low Noise Amplifier

Gallium arsenide(GaAs)-based monolithic microwave integrated circuit(MMIC)is widely used in many applications including microwave imaging,wireless communication,radar detection,and radio astronomy due to its excellent performance and the high reliability.The MMIC with compact size,high-performance,low power consumption has been extensively investigated in recent years.MMIC low noise amplifier(LNA)is located at the front-end of receivers,which is the first stage active circuit.The performance of the LNA are critical to the noise and sensitivity for the receivers.In this thesis,the process model was studied initially,and then the model parameters of the inductor and capacitor were extracted and validated.On the basis of model research,a Ku band MMIC LNA with three stage common source topology was demonstrated using 0.18 ?m GaAs pseudomorphic high electron mobility transistor(PHEMT).Self-biasing technique is employed for the convenience of chip test and use.In the first stage of the LNA,series source negative feedback bring the best noise and input conjugate matching impedance closer,as well as enhance the stability of the circuit.Parallel feedback technique is adopted between the gate and drain of transistors both in the second and third stage of the LNA,which also improves the gain flatness.The input matching network is designed to meet the best noise matching and to achieve good voltage standing wave ratio(VSWR).And then in the inter-stage matching network,the chip dimension is reduced significantly by directly match the output of the previous stage to the input of the next stage.Moreover,in order to facilitate the use of the chip in modules,the output stage is matched to 50 ohms in the output matching network.The modeling of the passive devices and the circuit design method could be used for reference to design the MMIC LNA.The layout simulation results show that,the noise figure of the MMIC LNA is less than 2.2 dB in the frequency range of 12-18 GHz,the gain is 25.7±0.5 dB,and the input/output VSWR is less than 1.8.The indications could meet the requirements of the applications such as point-to-point communication and phased array radar.