Investigation of interconnect loss due to coupling between two parallel microstrip lines in high-speed design

Loss due to coupling between two parallel microstrip lines is investigated in this paper. It is found that the transmission characteristic of the aggressor line was impaired by coupling. Most energy would be coupled to the victim line at resonant frequencies determined by the space between traces and the coupled length, which seriously affects the transmitted signals with high data rate. Two coupled microstrip lines are analyzed in terms of even and odd modes to explain this additional loss mechanism. Several design parameters are simulated. It is clearly shown that resonant frequencies increase with the space between traces and decrease with the coupled length. Electromagnetic simulations are also performed to illustrate this extra loss mechanism. Good agreement is seen between analytical and experimental analyses. (c) 2007 Wiley Periodicals, Inc.