Hi

Mechatronics Engineering is itself a specilized branch. It is a mixture of mechanical, electronics and electrical. Now as far as GATE exam is concerned no seprate paper  exists for Mechatronics.

So you are left with following papers which are closely related to mechatronics enginering.

1. Mechanical

2. Electronics and communication

3. Electrical

Now you have to make choice between this.

I can give you few pointers based on which you can take decision.

1. Check for GATE syallbus of those above 3 papers and try to compare with your mechatronics subjects whichever is closely related choose that.

2. Based on your prospects like in which PSU you want to work.

3. Higher studies specilization subject. 

Hello aspirant, 

You can write GATE exam in mechanical, electrical, electronics. But you better go with mechanical.Becuase there are no problem to take admission in M.Tech but PSUs companies are taking Mechatronics  branch who has given GATE in Mechanical Branch like BHEL etc