1. Electronics, Telecommunications and Information Technology, University Politehnica Bucharest, Bucharest 061071, Romania
2. National Institute for Research and Development in Microtechnologies, Erou Iancu Nicolae Street 126A, 077190 Bucharest, Romania
3. Centro Nacional de Microelectronica, C/del Til·lers. Campus Universitat Autònoma de Barcelona, 08193 Barcelona, Spain