Hi

I am to use a USB between a GSM module(Quectel BG95) and a microcontroller. The max speed will be 12 MB.

I have read that if you have EMC issues, then a transformer is needed, but it will reduce the speed.

Do we need to use a transformer between the module and microcontroller?

 

May be you cna post link to what you have read

USB is not AC coupled, so can not be transformer isolated,
A choke , common mode, can be used on the lines, to reduce EMI
but is not normally used if both ends of the link are on the same PCB,

I'd not be looking at a common mode choke,

https://www.digikey.co.uk/en/products/detail/coilcraft/0603USB-222MLC/15794223

 

Sorry, my error. Yes a common mode choke.

Yes both are ends are on the same PCB.

There is a possibility, that the module might need a firmware update, whereby, i would need to force the microcontroller in RST, while the module using a USB cable is programmed. But this is just once.