LDC1614: how to interpret application note SNOAA04A?

Hi all,

It has been a while since I have done any FEM simulation wrt magnetics, so I would appreciate some clarification wrt the application note SNOAA04A and how to translate this to my own coil design (as I'm having issues getting the Excel macros to run a FEMM, but also I'm just curious on the specifics to be honest). The design I'm trying to simulate can be found as an attachment, being Excel_FEMM_v1p29.xlsm.

This details a circular coil for the LDC1614 with a diameter of 26.88mm, 2 layers (one on top layer of PCB and one on bottom layer of PCB, e.g. 1.6mm PCB) and 22 turns on each layer. Trace width and all other details can be found in the Excel file. 

What I cannot remember is how to convert the coil design into a FEM model. I know that I have to use an asymmetric simulation, as I can exploit the symmetry in the circular coil. It's also fairly simple to draw one single trace, create the trace spacing and draw another one. But when you have to create circuit, there is a number of turn requested and I'm not sure how to interpret this.

E.g., do I have to create two traces of one layer and assign 22 turn to that circuit? Like this figure below. With an asymmetric problem, I have to define the boundary conditions such that the center of the boundary conditions is the correct distance away from the innermost turn of the coil. 

Or do I create 22 traces with corresponding traces and assign 1 turn to it? It's probably very trivial, but if someone could provide me with an answer that would be great.

Many thanks in advance!

Kind regards,

Jim

2821.Excel_FEMM_v1p29.xlsm