4 October 2023

Digital Technology Guru

Digital Technology Guru Reviews

Using Periodic Microstrip Lines to Reduce Signal Crosstalk in High-Speed Digital Circuits

2 min read
Using Periodic Microstrip Lines to Reduce Signal Crosstalk in High-Speed Digital Circuits

Signal crosstalk is a common problem in high-speed digital circuits, leading to reduced performance and electromagnetic interference. Traditional methods of reducing crosstalk, such as enlarging circuit area or increasing line intervals, can be detrimental to miniaturization and speed. In this article, we propose a new approach using periodic microstrip lines to mitigate signal crosstalk.

By adjusting the lattice constants and geometric parameters of periodic microstrip lines, it is possible to achieve a time domain characteristic impedance that is equivalent to conventional microstrip lines. This allows for tricking high-speed digital signals, causing them to misjudge the characteristic impedance of the transmission lines. The effectiveness of this approach has been verified through theoretical analysis and experimental measurements.

Previous methods, such as using grounded guard traces, have limitations in terms of resonance coupling and adverse effects on circuit miniaturization. Thus, researchers have explored alternative schemes, including stub-alternated microstrip lines and microstrip lines with periodic texture etched on the edges. These approaches have shown promise in reducing electromagnetic interference.

To facilitate the application of periodic microstrip lines in actual circuits, it is important to determine the characteristic impedances and equivalent circuits. Researchers have developed circuit models and extracted circuit parameters to calculate the (S)-parameters and simulate circuit performance.

In this work, an equivalent network method is used to derive the exact expression for the characteristic impedance of lossless transmission lines with periodically modulated capacitances and inductances. These characteristic impedances are dependent on the capacitances and inductances of the unit cells in the periodic structure. Accurate extraction of these parameters allows for achieving the desired low-frequency characteristic impedance.

In conclusion, the use of periodic microstrip lines shows promise in reducing signal crosstalk in high-speed digital circuits. Further research and experimentation are necessary to fully explore the potential of this approach.

Source article: Abstract
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