Time Domain Assessment of Minimum FEXT by Tabbed Line Design

Tabbed lines have been demonstrated to be effective for the reduction of Far-End Crosstalk (FEXT) in coupled lines and data bus of microstrip type. A minimum FEXT can be identified by carefully designing the tab geometry, the tab-to-tab distance, and the percentage of the tabbed portion of the microstrip with respect to the entire length. This paper evaluates the time domain performances of tabbed lines to verify their performances in terms of FEXT minimization. The induced FEXT pulse and the eye diagram metrics are used to demonstrate the tabs impact to reach a minimum FEXT. The dB level of the FEXT S-parameter that is necessary to reach to minimize the eye closure is derived while analyzing both DDR4 signals running at 3.2 Gbps and DDR5 signals running at 4.8 Gbps.