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16 The PCB Design Magazine • October 2014 CMP-28/32 platform contains 2- and 8-inch segments of single-ended stripline and mi- crostrip traces and 2- and 6-inch segments of differential stripline and microstrip traces that can be used to extract or confirm dielectric and conductor roughness models. We start with the single-ended stripline and first extract reflectionless GMS-parameters for 6-inch segment from the measured data shown in Figure 3 (red and blue lines with stars). The useful range of the GMS-parameters is about 30 GHz for the insertion loss and 40 GHz for phase delay (restricted by the manufacturing variations). Next we build a model of a 6-inch stripline segment with quasi-static field solver and first define dielectric model as the wide - band Debye (AKA Djordjevic-Sarkar) [7] with dielectric constant Dk=3.66 and loss tangent LT=0.0117 as specified for Isola FR408HR mate- rial at 1 GHz. To match the measured and modeled phase delay as shown in Figure 3, the Dk in the mod- el needed adjustment from 3.66 to 3.815. This adjustment can be explained by the anisotropy of the composite dielectric. To match measured and modeled generalized modal insertion loss, we have two choices—increase the loss tangent or model conductor roughness. We choose to simulate conductor roughness with the sim- plest Modified Hammerstad model [7] , defined SINk OR SWIM AT 28 GBPS continues feature Figure 2: Example of formal quality evaluation in Simbeor software for a subset of S-parameters measured for CMP-28 platform.