A.S. Bankovsky - Ph. D. (Phys.-Math.), Associate Professor, Department «Electronic devises and equipment», Yuri Gagarin State Technical University (Saratov) A.A. Zakharov - Dr. Sc. (Eng.), Professor, Department «Electronic devises and equipment», Yuri Gagarin State Technical University (Saratov). E-mail: zaharov@sstu.ru A.A. Ivanova - Student, Department «Electronic devises and equipment», Yuri Gagarin State Technical University (Saratov). E-mail: anastasia.acia@gmail.com