Development Of X-band Low Noise Amplifier

X-band(8～12 GHz)phased array radar systems are widely used in meteorological radar,satellite radar,detection radar,navigation radar and other fields.The transceiver(T/R)component is one of the most important components of the system,which can realize the signal amplification,phase shifting and attenuation functions.The low noise amplifier(LNA),as one of the core devices of the T/R component,realizes the first stage amplification of the received signal,which helps to improve the sensitivity of the receiver.Meanwhile,along with the rapid development of ultra-wideband technology and the gradual maturation of Ga As process,the research of wideband Ga As low-noise amplifier has been greatly promoted.Therefore,the main work and contributions of this paper are as follows:1.The stability of the self-biased LNA structure circuit is investigated,and a method to improve the stability of the LNA by connecting a series resistor to the drain of the first transistor stage is proposed.On this basis,an X-band LNA is developed,which is based on 0.5 um Ga As p HEMT process.The measured results show that the small signal gain is 13.5 d B and the gain flatness is less than ±0.4 d B.The LNA is stable in the full frequency band,which effectively verifies the feasibility of the proposed stability improvement method.2.To address the noise and gain flatness of broadband LNAs,the effect of source degradation inductive devices on the gain and bandwidth of microwave LNAs is investigated,the physical size of the source transmission line is optimized to obtain a high-quality factor transmission line to reduce the LNA circuit noise,and the gain flatness of broadband LNAs is further improved by inter-stage consumption matching.The results show that the gain flatness of the LNA is less than±0.4 d B,and the post-simulation results show that the noise figure is less than 1.53 d B in the operating band.3.Aiming at the power consumption and gain problem of broadband LNA,a circuit structure of three-stage cascade with current reusing is used to solve the demand of low power consumption under high gain of low noise amplifier.The LNA is based on a 0.5 um Ga As p HEMT process.Test results show that the LNA has a small signal gain of 22 d B and consumes as low as 28 m W.Meanwhile,based on the wafer-level heterogeneous packaging process,the paper designs the packaging of the LNA and proposes a co-simulation method that integrates the wafer-level packaging process with the Ga As process to evaluate the performance of the packaged LNA.The proposed co-simulation method provides a reference for microwave circuit packaging based on wafer-level processes and microwave solid-state integrated circuits to build heterogeneous microsystems.