Research of Suppressing Crosstalk of the Microstrip Lines by Using Stripe Protection

Reducing the crosstalk between coupled microstrip lines is very important for high-speed and high-density PCB. The crosstalk testing structure was established between PCB-coupled microstrip lines under the condition of termination match. Through finite element analysis and experimental test, the crosstalk between coupled microstrip lines has been investigated with or without metal filled via hole fence. The dependence of crosstalk with the width of stripe protection and grounding hole space between lines was examined. Numerical analysis and experimental results indicate that the best effect of crosstalk reduction can be obtained when an optimum value of stripe protection width is chosen, the attenuation of near-end crosstalk is 9 dB more compared with no strip protection and far-end crosstalk attenuation is 7 dB more. The crosstalk suppression of non-parallel microstrip lines using strip protection with increased width is equally effective. A critical space condition must be satisfied between protective grounding holes, while the radius variation of grounding hole does not affect the crosstalk. This research seems to be instructive for effective use of stripe protection to reduce crosstalk between microstrip lines.