Noise reduction using compensation capacitance for bend discontinuities of differential transmission lines

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 S-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