Optimization of Transmission Structures for Best Eye-Heights in High-Speed System Packaging
Date Issued
2016
Date
2016
Author(s)
Huang, Shih-Ya
Abstract
This dissertation focuses on designing the transmission structures in packaging to optimize the eye-height for high-speed systems, which becomes essential nowadays due to the ever-increasing data rate of signal and the limited layout area in packaging. To tackle the problems, design methodologies for several optimal transmission structures have been proposed to improve the eye-heights of both on board lines, i.e. the microstrip, and off board components, i.e. the flexible flat cable (FFC), in packaging. The structure of single-ended microstrip in a mismatched transmission line system is investigated by using the fast algorithm for predicting the eye height, in which the small errors between predicted and measured eye-heights show the accuracy of the method. The design contour map is also established versus the reflection coefficients at source and load ends of the transmission line systems. With the contour map, the best termination design for the transmission line system can be found in the condition when the impedance of transmission line is equal to the source resistor and the load is open circuit. Furthermore, for the transmission line system with arbitrary terminations at source and load ends, the optimal impedance design for the mircostrip is also proposed. Furthermore, consider two coupled microstrips in a restricted layout area, the design guidelines to optimize the eye-height are given when the transmission line system is with arbitrary terminations. The first guideline is to minimize the crosstalk noise by making the line space larger when the output reflection coefficient is positive. The second one is to make the transmission line impedance match to the output termination by widening the line width when the reflection coefficients are both negative. With the guidelines, the measured results show that the eye-height can be improved by 38.6 % at most in the performed cases. Finally, optimal design is rendered for the flexible flat cable (FFC) to eliminate the ringing noise and decrease the crosstalk noise by equalizing the modal velocities of the differential modes in FFC. With proposed design for the FFC, the eye-height improves about 30% compared to original design, and the radiation power decreases about 16 dBW. Similar improvement has been noticed even for the case of two pairs of differential signals.
Subjects
Optimization
eye-height
high-speed system
inter-symbol interference
reflection noises
crosstalk noise
modal analysis
microstrip
flexible flat cable (FFC)
Type
thesis
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