FAR-END CROSSTALK MODELING AND PREDICTION FOR HIGH-SPEED PCB DESIGN WITH INHOMOGENEOUS DIELECTRIC LAYERS (IDLS)
"Far-end crosstalk (FEXT) noise is a critical factor that affects signal integrity performance in high-speed systems. The FEXT level is sensitive to the inhomogeneity of the dielectric layers in fabricated printed circuit boards (PCB). The stripline is laminated by multiple inhomogeneous dielectric layers (IDL). The dielectric layers of the stripline are laminated with epoxy resin and glass bundles. The dielectric permittivity of the epoxy resin and glass bundles are different, which causes the inhomogeneity of the dielectric layers while also increasing the FEXT magnitude. The dielectric of the microstrip in printed circuit boards (PCB) fabrication usually consists of two layers: the solder mask layer and the substrate layer. In practice, the permittivity of the solder mask is generally higher than that of the substrate. Similarly, the inhomogeneity of the IDLs in the microstrip affects the FEXT and requires accurate characterization. In this work, a practical FEXT modeling methodology for striplines and microstrips is proposed by introducing the extraction method for the permittivity of IDLs. The new stripline model is constructed with three IDLs comprised of core, prepreg, and resin pocket, to improve the model accuracy The microstrip is modeled with the air, solder mask, and substrate layers. To analyze the stripline and microstrip with IDLs, a practical superposition method is proposed. In addition, an analytical model to predict the FEXT polarity and magnitude of the stripline caused by the inhomogeneity is proposed and targeted for pre-layout application. The proposed models can provide useful analysis methodology and design guidelines to mitigate the FEXT level in high-speed systems, especially for high-volume PCB tests in the pre-layout and post-layout stages"--Abstract, P. iv
Dielectric Material, Far-end Crosstalk, Signal Integrity, Electrical and Computer Engineering, Engineering
Missouri University of Science and Technology
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