Design Of Low Noise Amplifier And Mixer Using PHEMT Process

With more than 80 years of development,radio telescopes have made leap-forward improve-ments in sensitivity and observation efficiency.The future radio telescope observations need unprecedentedly high sensitivity and efficiency,which raise the higher requirements on the bandwidth,noise and beam of their receiver.The main technical bottlenecks of the receiver are low noise amplifiers?LNAs?,mixers,etc.,which determine the performance of the re-ceiving system to a large extent.A radio telescope needs to observe full-band signals in deep space.Compared with other band,the K-Band signal is easily absorbed by the water vapor in the atmosphere and reaches the ground with less intensity through the attenuation of the atmosphere.Therefore,higher performance LNAs and Mixers are required by K-Band receivers.Due to the large signal attenuation,the K-Band has long been considered unsuit-able for long-distance communication.There are few researches on the key technologies of K-Band receivers,which cannot meet the needs of future full-band radio telescopes.So,the research on the LNA and Mixer of K-Band receiver is of great significance.InGaAs Pseudomorphic High Electron Mobility Transistor?InGaAs pHEMT?,a heterojunction high mobility transistor,is widely used in RF receiver because of its low noise,high mobility and high gain.In the paper,the design method of K-Band ultra-wideband LNA and mixer are explored using the advanced technology of InGaAs pHEMT.In this paper,the main results are as follows:1.A K-Band three-stage ultra-wideband LNA is designed basing on WIN's 0.15?m InGaAs pHEMT device model.Solutions are provided to the problems of difficult matching,poor stability and difficult control of noise figure for multi-stage low noise amplifiers.The proposed three-stage LNA compensation matching technology,using the inductance and transmission line,is applied to improve the gain flatness of the K-Band,achieve the wide bandwidth and balance the contradiction of gain and noise figure.The resistance absorption and the source-level feedback are used to increase the stability of the circuit.Finally,the frequency of ultra-wideband LNA ranges from 18 to 26 GHz with the average gain(S₂₁)of 26 dB and the gain flatness of 1.7 dB.The simulated results show that the 1-dB compression point is 3.3 dBm,the noise figure is less than 2.2 dB at 300 K and the DC power consumption is 48 mW.It is absolutely stable in the full band.The layout area is 2000?m×900?m.2.A Cascode K-Band ultra-wideband mixer is designed based on WIN's 0.15?m InGaAs pHEMT device model.To overcome the shortcomings of the traditional Cascode structure,a modified bias Cascode topology is proposed.The mixer operating mode under different bias conditions is analyzed and the optimal operating mode suitable for the device process is selected for design.Finally,the mixer's intermediate frequency?IF?output frequency ranges from 2 GHz to 10 GHz.Simulation results show that the conversion gain of the mixer is higher than-7.5 dB and the variation range is within 2.6 dB under the input of the local oscillator?LO?frequency of 28 GHz and power of 0 dBm.The mixer's LO-RF,LO-IF,and RF-IF isolations are-23 dB,-33 dB,and-42 dB,respectively.The layout area is 1500?m×870?m.3.The LNA and Mixer designed above are connected to form a low noise down converter system.The simulation results show that when the RF input frequency is 18?26 GHz and the LO input signal frequency is 28 GHz with the power of 0 dBm,the IF output frequency of the system is 2?10 GHz,the average conversion gain is 19.5 dB and the noise figure is less than 4.5 dB,which meets the requirements of K-Band radio telescope receivers.