In between MBA and M.Tech you should choose one according to your interest and knowledge. After completing B.Tech Electronics and Communication Engineering you are eligible for the both courses.

I would suggest you to do M.Tech Electronics and Communication Engineering, as it is relevant to the b. tech and it will provide you immense employment opportunities rather then MBA.

For your reference here I am giving you the list of top Electronics & Communication Engineering Colleges:

Indian Institute of Technology Kharagpur (IIT KGP) Kharagpur
Indian Institute of Technology Roorkee (IIT Roorkee) Roorkee
Birla Institute of Technology and Science (BITS-Pilani) Rajasthan
Indian Institute of Technology - Banaras Hindu University (IIT-BHU) Varanasi
Indian Institute of Technology (IIT Guwahati) Guwahati
National Institute of Technology, Tiruchirappalli Tiruchirappalli
National Institute of Technology Warangal
National Institute of Technology, Surathkal Mangalore
Birla Institute of Technology.. Patna
Jadavpur University (Faculty of Engineering & Technology) Kolkata
International Institute of Information Technology, Hyderabad (IIIT-H) Hyderabad
Netaji Subhas Institute of Technology Delhi/NCR
Indian Institute of Information Technology, Allahabad Allahabad
Motilal Nehru National Institute of Technology Allahabad
PSG College of Technology Coimbatore
PEC University of Technology Chandigarh
Bengal Engineering and Science University West Bengal
Malaviya National Institute of Technology Jaipur
Visvesvaraya National Institute of Technology Nagpur
Thapar University Patiala
National Institute of Technology, Rourkela Rourkela
College of Engineering Pune Pune
Manipal Institute of Technology, Karnataka Manipal
Jawaharlal Nehru Technological University Hyderabad Hyderabad
R.V.College of Engineering Bangalore
Veermata Jijabai Technological Institute Mumbai
University College of Engineering (Osmania University) Hyderabad
Sri Sivasubramaniya Nadar College of Engineering - Tamil Nadu Tamil Nadu
Sardar Vallabhbhai National Institute of Technology Surat
Maulana Azad National Institute of Technology Bhopal
Nirma University - Institute of Technology Ahmedabad
BIT Sindri Dhanbad
Coimbatore Institute of Technology (CIT) Coimbatore
Vellore Institute of Technology (VIT) Vellore
Maharashtra Institute of Technology Pune
National Institute of Engineering, Mysore Mysore
National Institute of Technology, Jamshedpur Jharkhand
BMS College of Engineering Bangalore
National Institute of Technology, Durgapur Durgapur
Amity School of Engineering and Technology Delhi/NCR
University Visvesvaraya College of Engineering - Karnataka Bangalore
Amrita Institute of Technology and Sciences - Tamil Nadu Coimbatore
Chaitanya Bharathi Institute of Technology Hyderabad
College of Engineering Trivandrum Thiruvananthapuram
Bangalore Institute of Technology Bangalore
SASTRA University Thanjavur
Jawaharlal Nehru Technological University, Kakinada Andhra Pradesh
Thaigarajar College of Engineering Madurai
National Institute of Technology, Hamirpur Himachal Pradesh
University Institute of Engineering & Technology Chandigarh
PES Institute of Technology Bangalore
National Institute of Technology, Raipur Raipur
The Icfai Institute Of Science & Technology Hyderabad
National Institute of Technology, Patna Patna
Gandhi Institute of Technology and Management (GITAM) University Visakhapatnam
Shri Ramdeobaba College of Engineering and Management Nagpur
Sona College of Technology Salem
Karunya UniversityRequest E-brochure Coimbatore
Dwarkadas J. Sanghvi College of Engineering Mumbai
Sathyabama University Chennai
Kongu Engineering College Erode
Government College of Engineering (Amravati) Amravati
Guru Nanak Dev Engineering College Ludhiana
Acharya Institute of Technology Bangalore
Shri Dharmasthala Manjunatheshwara College of Engineering and Technology Dharwad
Dr B R Ambedkar National Institute of Technology Jalandhar
Faculty of Engineering and Technology, Jamia Millia Islamia Delhi/NCR
Shri Govindram Seksaria Institute of Technology and Science Indore
Amrita School of Engineering Bangalore
Sir M Visvesvaraya Institute of Technology Bangalore
Rungta College of Engineering & Technology Bhilai
KLE Dr. M S Sheshgiri College of Engineering and Technology Belgaum
SCMS School of Engineering and Technology Kochi