"that a PCB manufacturer would plot the gerber data as-is."
if we tell them not to do impedance control on this board, then they will not. what i described above: i made impedance control on a board, then they wanted as well, they sent me their results and those were less accurate than mine.
they measured by TDR (probably with incorrect rise times, but even then), and these were the results on my 60ohm@1.2GHz traces:
Code:
REQUIREMENT MEASUREMENT
NOMINAL TOLERANCE MINIMUM MAXIMUM
58 10% 60 61
they say my requirement was 58?????? it was 60@1.2GHz, which is 58.7@1MHz. ad with a TDR probably they setted up a sort rise time: 30ps...600ps where 410ps would be my signal rise time. from my trace widths they have calculated back the 58 ohms. do i have to explain more?
Added after 5 minutes:
so everyone says i shouldnt care about it, let the pcb fab to do that.
i know how to let them to do that, but i dont know how to make the equations. my question was about this.
it doesnt mean that then i will give up. i know most of the designers let the fab to do that, but i dont care. what i care about is the equations.