Solving the Field Solver Typo'

摘要

If you have ever used a 2D field solver to calculate the far-end crosstalk coefficient (FEXT) in a pair of microstrip transmission lines - a critical part of every design with surface traces! - you've probably encountered what appears to be a typo or a bizarre result. In a pair of tightly coupled microstrip traces, commonly found on all four-layer boards and many higher layer count boards, crosstalk can be a huge potential problem. Estimating what to expect before you build a board is always a good habit. A simple rule of thumb can estimate whether a field solver is needed to confirm a potential problem, or whether you have plenty of margin and can sleep well at night.