After you Btech, you will have to apply for GATE exam and therefore you can do Mtech in Electronics and Instrumentation engineering, the same field of your interest. Similar courses of this field you can choose from are Power Electronics, Electronics Product Design Technology, Electronics and Power Engineering, Electronics and Media Technology.

This course is perfect for the ones who see their future developing and designing innovative instruments and systems for various industries.

Some of the colleges which provide this course are:

SRM University

CoeP

Indian Institute of Science

Sastra University.

You can details about this course here. 

Good Luck.