Reducing glitches when reconstructing four‐port S‐parameters of differential transmission lines from two‐port measurements

Garcia-Mora, Daniel M.; Tlaxcalteco-Matus, Miguel A.; Torres‐Torres, Reydezel; Hernandez-Sosa, Gaudencio; Becerra-Fuentes, Olga M.

doi:10.1002/mop.28568

Cited by 1 publication

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References 10 publications

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“…In 1997 Bockelman continued his work and provided a conversion formula for mixed-mode S-parameters from single-ended Sparameters [2] for the case with no coupling. A lot of research has been done on this topic including theoretical development, conversion from and to single-ended S-parameters, and simulation and measurement comparisons [3], [4], [5], [6], [7]. It is clear from this literature that the coupling between the interconnects plays a critical part in this conversion.…”

Section: Introductionmentioning

confidence: 99%

A Study of Differential Signaling: Stable and Accurate Mixed-Mode Conversion and Extraction of Differential S-Parameters

Tran

Barannyk

Elshabini

et al. 2015

2015 IEEE Workshop on Microelectronics and Electron Devices (WMED)

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Low voltage differential signaling (LVDS) in highspeed digital systems is utilized to effectively reduce EMI and improve signal quality. Mixed-mode S-parameters are a more general way to characterize a differential network. Therefore, an accurate extraction of mixed-mode S-parameters from singleended S-parameters is critical for Signal and Power Integrity co-simulation where SSN is generated mainly by high-frequency interconnects. The standard conversion between mixed-mode and single-ended S-parameters involves inversion of a transformation matrix. If there is no coupling, this transformation matrix is orthogonal and numerical inversion can be done accurately. In the presence of coupling, the transformation matrix depends on S-parameters and may become ill-conditioned, i.e. has high condition number, for some values of physical parameters resulting in unstable inversion of the transformation matrix and leading to highly inaccurate converted mixed-mode S-parameters. To analyze the possibility of ill-conditioning, we consider two cases: broadside coupled striplines and coupled microstrip pairs. We find that in both cases when two transmission lines are strongly coupled, the condition number becomes very large. In this case, regularized methods from the theory of ill-posed problems should be used, for example, the truncated SVD method, to obtain accurate mixed-mode S-parameters. Index Terms-differential S-parameters; S-parameters; signal integrity; conversion matrix; accurate conversion; condition number 978-1-4799-7380-4/15/$31.00 ©2015 IEEE

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