Parameters optimization of the HEMT-transistor equivalent circuit

Most domestic and foreign transistors, as a rule, do not have computer models compatible with modern computer-aided design systems. This is largely explained by the complexity of solving the corresponding optimization problems of determining a set of parameters for an equivalent transistor model. The relevance of the work carried out is associated with the lack of modern element base in the libraries of well-known computer CAD systems, which significantly limits the possibilities of designing specific devices. The article presents the main stages of modeling the low-noise HEMT-transistor FPD6836P70. The basic model of the transistor has more than 60 parameters, the optimization goals are eight experimentally frequency (amplitude and phase of S-parameters in an ultra-wide operating range) characteristics of the FPD6836P70 transistor. Thus, the problem of determining the values of the parameters of the basic transistor model belongs to a complex class of so-called multicriteria multiparameter optimization problems. Since existing computer methods for searching for optimal solutions do not have a universal algorithm suitable for solving any optimization problem, solving specific optimization problems requires the development of an individual approach. The goal of the simulation was to obtain calculated characteristics that were as close as possible to the measured frequency characteristics of the transistor. The article describes a methodology for modeling frequency characteristics based on the common basic model of the EEHEMT-transistor. The article defines a set of parameters of the transistor equivalent circuit that affect the frequency characteristics. The optimal numerical values of the parameters of the equivalent circuit EEHEMT are found, and the results of calculations of a family of frequency characteristics of the transistor are presented. The corresponding problems of parametric optimization are formulated and solved. Experimental frequency characteristics of the HEMT were used as optimization goals. The technical novelty of the solution to the problem presented in the article lies in the division of the general problem into two subtasks: optimization of static and frequency characteristics. This approach makes it possible to reduce the complexity of individual subtasks, since the number of parameters and optimization goals is reduced. The analysis of the obtained results shows that the calculated frequency characteristics differ from the measured ones by no more than 21%. The article describes a methodology for modeling the frequency characteristics of the FPD6836P70 transistor based on the common basic model EEHEMT. A set of parameters of the transistor equivalent circuit that affect the frequency characteristics is determined. The optimal numerical values of the parameters of the EEHEMT equivalent circuit are found, and the results of calculations of the family of frequency characteristics of the FPD6836P70 transistor are presented.