how do i make controlled impedance trace
I have a 6 layer-board with 10-mil spacing layers and FR4 material. My 50-Ohm trace is on component side and the ground layer is the next layer (10-mil distance).
Using the formulas, I found that the trace should be around 17 mils thick to obtain the 50-ohm controlled impedance.
For EMI reasons, I did a ground fill on the component side but I kept a clearance around the controlled impedance trace to avoid affecting the controlled impedance.
What should be this clearance? Some say 3 times the trace width. Some say 3 times the "ground plane to trace" distance. What do you think?
Best regards, T.