Better transmission line modeler for Affirma 4.4.6?

Hello!

Please help! I am in serious need of a way to model 3-dimensional groups of
transmission lines for simulation in Affirma Analog Environment / Artist
version 4.4.6.

Right now I'm using the transmission line modeler that's included in
Affirma. It seems to generate good capacitance and inductance matrices for
transmission lines (striplines) placed in 2 dimensions (lines placed next to
each other), but we're currently designing boards with striplines placed
next to each other as well as on PCB layers above and below other lines. I
believe FastHenry and FastCap from MIT have this ability (as well as several
commercial tools), but I need to perform all my simulation in Affirma. Any
ideas?

Thanks in advance!
-Jason

 

Hi,

As far as I know FastHenry is able to write out Spice subcircuits for
your transmission line model.
Affirma Analog Env. or Spectre should be able to read them,
if not try to convert them into spectre subcircuits with 'spp'
(SPICE Reader), it comes with the Cadence installation.
Just type spp in your terminal or spp -help.

Regards Bernd

 

You should also take a look at lmg in IC5032 or IC5033. A lot of improvements
were made in IC50 and later - for example, handling dieletric loss, more
flexibility in specifying the lines, co-planar waveguide etc.

Using a .initlmg file:

lmgLineType = Others
lmgModelType = LossyWide
lmgSubcktFormat = 0
lmgNumLayers = 1
lmgNumLines = 4
lmgNumGndPlanes = 1
lmgLengthUnit = um
lmgFreqUnit = GHz
lmgDielectricPermittivity = 3.4
lmgDielectricThickness = 200
lmgLossSigmaLossTang = VSIGMA
lmgDielectricConductivity = 0.0
lmgGndThickness = 20
lmgGndSigma = 5.6e7
lmgConductorWidth = 300
lmgConductorGaps = -300
lmgConductorThickness = 20
lmgConductorHeight = 50 100 150 200
lmgConductorLength = 5000
_lmgConductivity = 5.6e7
lmgMaxFreq = 10
lmgSubCircuitName = tline
lmgLRCGName = w_line.dat
lmgOutputID = RLCG

shows how to create 4 lines stacked on top of each other (for example). You can
produce an RLGC file with frequency dependent RLGC matrices - these can
then be used with spectre's mtline component for an accurate model of the line
which behaves well over a wide frequency range.

Regards,

Andrew.