1. Institute of Technological Sciences, Universidade Federal de Itajubá,Itabira,Brazil
2. Universidade Federal de Minas Gerais,Department of Electronics Engineering,Belo Horizonte,Brazil
3. Universidade Federal de Minas Gerais,Graduate Program in Electrical Engineering,Belo Horizonte,Brazil
4. Universidade Federal de Minas Gerais,Department of Electrical Engineering,Belo Horizonte,Brazil