International Journal of Electrical and Computer Engineering (IJECE) Vol. 10, No. 1, February 2020, pp. 129~138 ISSN: 2088-8708, DOI: 10.11591/ijece.v10i1.pp129-138  129 Journal homepage: http://ijece.iaescore.com/index.php/IJECE A genetic algorithm for the optimal design of a multistage amplifier El Beqal Asmae 1 , Bachir Benhala 2 , Izeddine Zorkani 3 1,3 Faculty of Sciences Dhar el Mhraz, University of Sidi Mohamed Ben Abdllah, Morocco 2 Faculty of Sciences, University of Moulay Ismail, Morocco Article Info ABSTRACT Article history: Received Sep 19, 2018 Revised Aug 8, 2019 Accepted Aug 29, 2019 The optimal sizing of analog circuits is one of the most complicated processes, because of the number of variables taken into, to the number of required objectives to be optimized and to the constraint functions restrictions. The aim is to automate this activity in order to accelerate the circuits design and sizing. In this paper, we deal with the optimization of the three stage bipolar transistor amplifier performances namely the voltage gain (AV), the input impedance (ZIN), the output impedance (ZOUT), the power consumption (P) and the low and the high cutoff frequency (FL,FH), through the Genetic Algorithm (GA). The presented optimization problem is of multi-dimensional parameters, and the trade-off of all parameters. In fact, the passive components (Resistors and Capacitors) are selected from manufactured constant values (E12, E24, E48, E96, E192) for the purpose of reduce the cost of design; also, the intrinsic parameters of transistors (hybrid parameters and the junction capacitances) are considered variables in order not to be limited in design. SPICE simulation is used to validate the obtained result/performances. Keywords: Genetic algorithm Metaheuristic Optimization Three-stage bipolar transistor amplifier Copyright © 2020 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: El Beqal Asmae, Faculty of Sciences Dhar El Mhraz, University of Sidi Mohamed Ben Abdllah, Fez 30050, Morocco. Email: asmae.elbekkal@gmail.com 1. INTRODUCTION Despite the strong trend towards integrated circuits, discrete components are still used in analog design especially for circuits that are not produced in large quantities. Discrete components such as Resistors (R) and Capacitors (C) are produced according to the industrial series such as E12, E24, E48, E96 or E192. To reduce costs and make the design faster, discrete components are selected according to values constants of the previous series. An exhaustive search of all possible combinations of values for selection of an optimized design is not always feasible. On other hand, almost all the design of analog circuits has been oriented towards MOS transistor- based circuits mainly due to their low power consumption. Studies that address the sizing of circuits based on bipolar transistors remain very scarce although they have better speed (switching times) and wider bandwidths [1]. In addition, these studies deal with design considering the intrinsic parameters of bipolar transistors as fixed, such as the works [2, 3] where an usual analog circuits are sized in which the current gain (β) and the base- emitter and base-collector junction capacitances (Cπ) and (Cµ) are considered as fixed which limits the design and subsequently reduces the performance of these circuits. In order to overcome the aforementioned difficulties and limitations, an intelligent and efficient optimization technique requires short computation time with high accuracy, must be used. Methods based on the use of Meta-heuristics appeared then to resolve complex optimization problems, they always offer