FULL-WAVE MODELING OF MULTIPLE VIAS USING DIFFERENTIAL SIGNALING AND SHARED ANTIPAD IN MULTILAYERED HIGH SPEED VERTICAL INTERCONNECTS

Abstract

A 3D full-wave approach, based on the Foldy-Lax multiple scattering equations, is successfully extended to model massively- coupled multiple vias using difierential signaling and shared antipad in high speed vertical interconnects. For the flrst time, this method has been used and tested on via-pair with shared antipad in multilayered structure. The magnetic frill current source on the port is calculated by using the flnite difierence method. Banded matrix iterative method is applied to accelerate the flnite difierence calculation. Numerical example of 15 signal via-pairs and 20 ground shielding vias in 6- layer board demonstrates that this approach is able to model the via-pair with shared antipad and to include all the coupling efiects among multiple vias. The electrical performances of difierent signal driving schemes are provided and discussed. The coupling crosstalk on various via-pairs is compared. The improvement of signal integrity is shown by using difierential signaling and shared antipad for via-pair in multilayered structure. The results are compared with HFSS and SIwave in accuracy and CPU. The CPU using Foldy-Lax approach is three orders of magnitude faster than using HFSS, and two orders of magnitude faster than using SIwave. The accuracy of Foldy-Lax is within 2% difierence from HFSS up to 20GHz, and outperforms SIwave in accuracy.