Computerized optimization of multi-layered and/or multi-trace microstrip-lines for reduced cross-talk interference

• Published in: Computers & electrical engineering 1997, Vol.23 (3), p.165-177
• Main Authors: Lu, L., Ungvichian, V.
• Format: Article
• Language: English
• Subjects: Analog circuits; Applied sciences; Circuit properties; Crosstalk; Electric, optical and optoelectronic circuits; Electromagnetic compatibility; electromagnetic interference (EMI); Electronic circuits; Electronics; Exact sciences and technology; Information, signal and communications theory; microstrip lines; printed circuit board design; spectrum domain analysis; Telecommunications and information theory; ultra-speed clock
• ISSN: 0045-7906; 1879-0755
• DOI: 10.1016/S0045-7906(97)00002-5

In parallel microstrip-lines, the ratio of the thicknesses of two substrates is adjusted in the so-called compensated-substrate structures so that the propagation speeds of even and odd modes are made identical and cancel each other facilitating a reduced interline cross-talk interference. This paper presents an extension of the compensated-substrate approach to more complex microstrip structures such as four and eight parallel lines on a multi-layer board. Unlike the two parallel microstrip-lines, the perturbation of substrate thickness-ratio alone would not facilitate minimum cross-talk conditions in the multi-trace/multi-layer structures. Therefore, in such cases, say, for example, in four or eight microstrip lines laid on two-layer substrates, the cross-talk can be reduced by optimizing not only the ratio of compensating substrate thicknesses, but also the other dimensional parameters of the structure. Pertinent design warrants a multi-variable optimization computational procedure which is elaborated in the present study. Development of relevant optimization algorithms use the Spectral Domain Approach (SDA) in conjunction with the Fourier Transform (FT) method; and, the associated numerical method of solving for the design parameters are presented here. Further, typical test results are furnished which indicate the feasibility of achieving an interline cross-talk reduction of 76% at a given distance of 40 mm from the source-end excited with a 25 × 10 −12 s Gaussian pulse.