The effects of substrate permittivity and pulse-width on the crosstalk as applied to ultra-high-speed microstrip lines

The crosstalk of parallel microstrip lines is investigated with an emphasis on important parameters such as substrate permittivity (/spl epsiv//sub r/), pulse-width (/spl tau/) and line-length. The technique utilized here is based on the Fourier and linear system theory. Several closed form expressions for the frequency-dependent parameters are included in the simulations. From the simulations using an ideal Gaussian pulse source, the results suggest that for a wider pulse-width (/spl tau/>10 ps) the crosstalk is proportion to /spl epsiv//sub r/, but for very narrow pulses (/spl tau//spl les/10 ps), the crosstalk is either reduced or relatively the same for /spl epsiv//sub r//spl ges/9.7. Also, for a narrow pulse (/spl tau/=5 ps), the crosstalk depicts an oscillatory level along the line. At 30 mm, a 5 ps pulse produces less crosstalk than the 10 ps pulse.