I got a score of 641 in gate 2019 ECE. I belong to OBC catagory. My rank is 1567.Is there any chance of getting Microelectronics in top IIT?

The cutoff for microelectronic for IIT Madras is 698 and for IIT Bombay it's 777 . They are previous year cutoff based on score.

As per your score and previous year cutoff, the colleges you get in first round are:-

• National Institute of Technology Calicut Department of Electronics & Communication Engineering Microelectronics & VLSI Design
• Motilal Nehru National Institute of Technology Allahabad Department of Electronics & Communication Engineering Microelectronics & VLSI Design
• National Institute of Technology Durgapur Department of Electronics & Communication Engineering Microelectronics & VLSI
• National Institute of Technology Patna Department of Electronics & Communication Engineering Microelectronics & VLSI Design
• National Institute of Technology Uttarakhand Department of Electronics & Communication Engineering Microelectronics & VLSI Design
• National Institute of Technology Silchar Department of Electronics & Communication Engineering Microelectronics & VLSI Design
• National Institute of Technology Srinagar Department of Electronics & Communication Engineering Microelectronics
• National Institute of Technology Sikkim Department of Electronics & Communication Engineering Microelectronics & VLSI Design
• National Institute of Technology Mizoram Department of Electronics & Communication Engineering Microelectronics and VLSI System Design

To know more about your chances of getting other colleges check out the PSU/college predictor link below:

https://engineering.careers360.com/gate-college-predictor

Sorry to say you but with rank getting old IITs and micro electronics department is very hard.You can get new IITs and good nits as per your preference. But getting old IITs are very hard for you.You can also check your possible IITs and nits at careers360 college predictor section.