I.V. Borodenkova - Post-graduate Student, Department «Electronic devises and equipment», Yuri Gagarin State Technical University of Saratov. E-mail: irinka0483@mail.ru V.A. Tsarev - Dr. Sc. (Eng.), Professor, Department «Electronic devises and equipment», Yuri Gagarin State Technical University of Saratov. E-mail: tsarev_va@mail.ru