| With continuous development of satellite navigation technology,global navigation satellite system(GNSS),including US GPS,China Compass,Russia GLONASS,European Galileo and other navigation satellite systems are widely used.Although the signal frequencies of the four navigation satellite systems are distributed differently,they are all concentrated in the 1170 to 1610 MHz frequency band.This brings great opportunities for the design of RF front-end devices that are compatible with multiple satellite signal bands.The satellite signal received by the receiver from the antenna is weak.Ambiguity noise is everywhere in the system plus the noise of the device itself.It will interfere with the satellite signal and affect normal communication.Research on front-end devices that suppress noise interference and amplify the satellite signal is particularly important.Therefore,research on front-end design cover full-band of GNSS system has important practical significance.In this dissertation,a high-performance low noise amplifier for full-band GNSS receivers is presented,a two-stage amplifier circuit structure is combined wide-band matching technology,and designed a wide-band low noise amplifier operate in the 1.1 to 1.7 GHz frequency range based on SMIC 0.18?m MMRF CMOS technology.The first-stage amplifier circuit of the wideband low noise amplifier uses cascode structure of source inductive negative feedback,the input matching network is composed of a Chebyshev bandpass filter structure,and the system bandwidth is expanded under the minimum noise figure;The second-stage amplification circuit adopts common source structure,and the output matching network uses ?-type matching to achieve conjugate matching to enhance system gain.The inter-stage matching network introduces parallel peaking technology combined with T-type matching to reduce input and output reflection coefficients and expand system bandwidth.At the same time,The active bias circuit is constructed using current mirror to provide a stable current for transistor,gate-drain RC parallel feedback and source inductor negative feedback form multiple feedback structures to boost system bandwidth and stability.Finally,ADS software is used to draw the schematic diagram,and a large number of simulation experiments are optimized.The simulation results show that the noise figure is less than 1.75 d B,the gain is greater than 25 d B,the input and output reflection coefficient is less than-11 d B,the power consumption is 16.5m W under the supply voltage of 1.8V,and the circuit is in an absolutely stable state.Therefore,the designed low noise amplifier is characterized by low noise and high gain while ensuring a wide operating frequency,meet the design requirements of low noise amplifiers. |
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