Design And Implementation Of Low Noise Amplifier With Dualband Filter

The rapid development of modern communication technology makes the performance of wireless communication devices more and more excellent.RF electronic devices play an important role in communication equipment,but also face the huge challenge of improving the performance.Low Noise Amplifier(LNA)and filter play an irreplaceable role in RF system.Nowadays,with the development of research,RF electronic devices are developing towards high performance,miniaturization,light weight and low cost.At the same time,due to the vigorous development of wireless communication field,many devices need to use multiple frequency bands at the same time,which promotes the development of communication equipment towards the direction of multi frequency.Therefore,this thesis uses a collaborative design method to design an LNA with dualband filtering function,which can achieve multi-band communication,and achieve the purpose of circuit miniaturization while improving the circuit performance.This thesis firstly introduces the basic theory of LNA design,and gives the main performance parameters of LNA design.According to the design ideas and performance parameters requirements,through the electromagnetic simulation software ADS for simulation design,a two-stage LNA working in the S-band is designed.After optimization,the design scheme is obtained and processed into a real object.The experimental results of two-stage LNA show that the Noise Figure is less than 1.12 dB,the Gain is more than 30 dB in the range of 2.3GHz to 2.6GHz.After that,the theoretical research and design method of multimode resonators are introduced,and four dualband filters based on multimode resonators are designed,manufactured and tested.It includes two four-mode dualband filters based on Stub Loaded Resonator,one with a measured center frequency of 1.75GHz/3.40 GHz and a Insertion Loss of 0.89dB/1.08 dB,the other with a center frequency of 2.0GHz/2.4GHz and an Insertion Loss of 1.21dB/1.6dB.At the same time,two dualband filters are designed based on Stepped Impedance Resonators(SIR).The test results show that one center frequency is 2.44GHz/5.71 GHz,the Insertion Loss is 2.31dB/2.42dB;the other center frequency is 0.98GHz/2.23 GHz,the Insertion Loss is 0.91dB/0.67 dB.The designed dualband filters have the characteristics of low Insertion Loss,high selectivity and compact structure.At last,a cooperative design method of LNA and dualband filter is used.By designing the input impedance of the filter as the conjugate of the output impedance of LNA,the 50? impedance matching network designed by the traditional unit circuit is eliminated.The output impedance matching and circuit filtering functions of LNA are realized simultaneously by the filter,which can improve the performance and reduce the size effectively.Finally,an LNA with dualband filter is designed,which works at 2.0GHz/2.4GHz.The Noise Figure is 0.44dB/0.67 dB,the Gain is 15.84dB/14.82 dB,and the size is reduced by 19.2%,which shows the feasibility of this kind of collaborative design method.