Crosstalk in multilayer printed circuit boards

Experimental measurements were conducted to study the problem of crosstalk in multilayer printed-circuit-board design. Experiments using both pulse and sinusoidal signals were designed to study crosstalk as a function of coupling line lengths, line spacings, and shielding versus nonshielding (lines in different layers). The mutual inductance and capacitance between two similar transmission lines were also extracted from simple models of crosstalk. It is found that when a sinusoid-driven signal was used as the voltage source, the coupled transmission lines acted as a transformer. The induced voltage on the passive line is approximately proportional to the square root of the coupling line length in the range of 2-20 in. These experiments can be used to enhance students' quantitative understanding of the problem of crosstalk in modern electronic circuit design