********** W element tline definition********** * * The following defines a two conductor w * element transmission line model for a dual * stripline board structure with 0.5 oz trace * thickness, 4 mil wide trace and 60 ohm target * characteristic impedance. The six mil separation * between the traces produces a diff impedance of * 99.2 ohms. This was calculated using the Polar * Instruments CITS25 Field Solver. This will model one * coupled differential signal pair. * Define the board material .MATERIAL diel_fr4 DIELECTRIC ER=4.1 +LOSSTANGENT=0.020 .MATERIAL copper METAL CONDUCTIVITY=5.8e+07 * Define the cross section of the trace, rectangle * 1/2 oz copper, 4 mil wide .SHAPE rect RECTANGLE WIDTH=4mil, HEIGHT=0.7mil * Define the dual stripline structure, two striplines * between two 2 oz pwr/gnd planes. Each trace is 5 mils * from the plane and five mils from the other trace. .LAYERSTACK dual_sl_60, + LAYER= (copper,2.8mil), LAYER=(diel_fr4,16.4mil), + LAYER= (copper,2.8mil) .FSOPTIONS opt1 PRINTDATA=YES + ComputeRo=yes ComputeRs=yes ComputeGo=Yes ComputeGd=yes + ACCURACY = HIGH .MODEL cond2_diff W MODELTYPE=Fieldsolver, +LAYERSTACK=dual_sl_60, FSOPTIONS=opt1, +RLGCFILE=cond2diff.rlgc, +CONDUCTOR= (MATERIAL=copper, SHAPE=rect, ORIGIN= (0, 7.8mil)), +CONDUCTOR= (MATERIAL=copper, SHAPE=rect, ORIGIN= (10mil, 7.8mil)) ****** End of the W element definition ****************************************************** * Example * define a 4 inch instance of the w element stripline * illustrated above. *W1 lvdsout1a lvdsout1b 0 OUTA OUTB 0 FSmodel=cond2_diff *+N=2 l=4000mil