Differential signaling has become a popular choice for multigigabit digital applications in favor of its low-noise generation and high common-mode noise immunity. Recalling from the full-wave solution of -parameters, this paper presented a design methodology of analysis scheme to extract the equivalent circuits of discontinuities observed on the strongly coupled differential lines. Signal integrity effects of the bent differential transmission lines in a high-speed digital circuit were then simulated in the time domain. A dual back-to-back routing topology of bent differential lines to reduce the common-mode noise was further investigated. To alleviate the common-mode noise at the receiver, a novel compensation scheme in use of the shunt capacitance was also proposed. Furthermore, the comparison between the simulation and measured results validated the equivalent circuit model, coupled bends with compensation capacitance patch, and analysis approach.

-Grounded guard traces are increasingly used to reduce the coupling-induced crosstalk, but the incurred ringing noise will strongly limit the performance for the microstrip structures. This paper describes the generation mechanism of the ringing noise and derives an analytical formula of the noise magnitude. Besides, an enhanced microstrip guard trace design is proposed to eliminate the ringing noise by covering the original microstrip structure with a superstrate of higher permittivity. A design space versus the superstrate thickness and the dielectric constant are constructed and in which, the guard trace needs be grounded at the two ends only without causing any ringing noise. Finally, the time-domain simulations and experiments are performed to verify the proposed concept.Index Terms -crosstalk noise, ringing noise, guard trace, noise suppression, dielectric superstrate, signal integrity.

In this paper, the split power planes with electromagnetic bandgap structures enhancement is proposed for the wideband suppression of ground bounce noise in high-speed printed circuit boards. A systematic design procedure is presented, featuring a modified analytic design formula, a novel compact electromagnetic bandgap layout, and a discussion on the minimum number of cascaded rows. As it is capable of selectively suppressing the ground bounce noise at several desired frequencies, the approach is applied to deal with the coupled noise between two isolation islands and the ground bounce noise induced by signal line crossing the split power planes. Successful noise suppression over an ultrawide band from dc to 5 GHz and reduction of the peak ground bounce noise in the time domain by 75% by an electromagnetic bandgap strip 1.44 cm wide is demonstrated. Good agreement is seen from the comparison between simulation and experimental results.

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