Hi Jim and Jian,
Thank you for your respond.
Jim,
I'm also agree with your claim about thickness.Simply
I assumed that in most today's RFIC the spacing is equal or smaller
than thickness,so you need thick model.
I'm aware of multi sheet model but it is not good for RFIC typical
crosssection in which current are pretty uniform at center and not zero
as this multy level model forces by interior levels.This model practic use
,probably, is in more thicker and wider conductors.
One of things I don't understand in Sonnet why is the current ratio default is zero?
For RFIC as I saw (you can easily see with 2 sheet model) and also
in more bigger crossection it is about 1 or some fraction bigger than ¼.
In fact as I understood the 0 CR is veryyy radical case.
About timing maybe except circular spirals (which I haven't tested) the rectangular
and octagonal inductor simulation are everagely bit slower from other
simulator , WHEN using differntial inductors which have diagonal
parts and some of them touching vias , with or without conformal mesh, the simulation time become much bigger than other tools,because of many
unneeded subsections.
Since we often simulate big structures and need to "scratch"
each MB
out of problem memory ,I think after 2 years ,I learned with Sonnet support help how to set porblem to achieve close to minimal simulation time.
Of course there is no general tool approriate for all cases,but if we narrow
application field enough I think there is.
Right now (maybe I wrong) I think the Momentum RF is best ( in terms of:
accuracy,simulation time and easy problem setup) for restrictions
I mentioned.
Jian,
Most of my IE3D comparison was done on many turns (High Inductance)
inductors
(For low inductanes the teststructure parasitics significant
so to avoid deembeding complications whole structure need to be simulated
I couldn't find ideal port setting for the problem ,so later on this year
I probably contact you about this issue).
In this many turns inductors I mostly look on inductance which is not
property of loss. It is hard do to mistake there since teststructe parasitics
are insignificant and return current was via inductor himself (and NOT for instance
through teststructure) this made also very easy problem setup.
In this test I found that IE3D had poorest results (I've used thick model)
For very long inductors all the tools gave not so accurate results and they all missed resonance freq.
One of the question on IE3D , is there ports that may refernced
to other ports without any metalic ,on which potential excited, and which put in layout between desired metals and introduce port parasitics in structure?
In Momentum it is simply reference port ,in Sonnet it is the box.
Jim & Jian
One of the question may be arisen from this letter why don't you have
some RF biased engines which can speed up the simulation moreover
it may reduce inaccuracy which MAY introduced when solving RF problems
with fullwave mode ?
By RF I mean high freqs but relativly lumped devices.
And yes I might be wrong in my conclusions as we all
Thank you,
and looking forward to working with you in order to get best results from your
newest EM solvers.