University of Guilan Computational Sciences and Engineering 2783-2503 4 1 2025 02 13 Optimum Design of a Microwave Low-Noise Amplifier by Means of Least Mean Square Error (LMS) Technique in S Frequency Band 125 134 8469 10.22124/cse.2025.29132.1090 EN Saeed Reza Ostadzadeh Faculty of Engineering, Arak University, Arak, Iran Sina Feyzi BSC student from Arak University, Arak, Iran Journal Article 2024 12 01 In this paper a low noise amplifier (LNA) in the frequency interval of [3-5] GHz is designed and optimized. The design process consists of three parts. At first, the stability of the bipolar junction transistor (BJT) is investigated. Simulation results show that it is unconditionally stable in the whole frequency interval. In the second part, the input and output matching networks are constructed in such a way that the desired transducer power gain (G<sub>T</sub>=10dB) and possible minimum noise figure (F<sub>n</sub>) are achieved simultaneously. In order to achieve approximately constant G<sub>T</sub> and F<sub>n</sub> in the desired frequency interval, the input and output matching networks are finally optimized using least mean square error technique. Once the optimization process is converged, variations of G<sub>T</sub> and F<sub>n </sub>in the whole frequency interval are respectively less than 1dB and 0.5 dB.  Besides, the variation of output phase is approximately linear.  LNA Optimization Power gain Noise figure Broadband https://cse.guilan.ac.ir/article_8469_10c063c2735e40204e5230afd8a1d4fb.pdf