V.A. Senchurov - Ph. D. (Eng.), Associate Professor, Department «Electronic Instruments and Devices», Yuri Gagarin State Technical University of Saratov E-mail: senchurov_v86@mail.ru V.Yu. Muchkaev - Ph. D. (Eng.), Associate Professor, Department «Electronic Instruments and Devices», Yuri Gagarin State Technical University of Saratov E-mail: muchkaev_vadim@mail.ru