Mixed-Mode S Parameters Theory And Its Application In Analysis Of Signal Integrity

As the systematic clock frequency is growing higher, signal's switch time is getting shorter, signal integrity problems caused by High-speed interconnection have been more and more critical and have become the most urgent issues in High-speed digital circuit design.Both of the time domain analysis and frequency domain analysis can be applied in the signal integrity analysis of High-speed circuits. When the interconnection and encapsulation structures which contain distributed components and frequency-dependent components being analyzed, compared with the traditional time domain analysis, the frequency domain analysis is more simple and convenient. Based on the results of the frequency domain analysis, the time domain response of High-speed pulse signals through the Fourier transform can be achieved.Firstly, the relevant theories about High-speed Signal Integrity analysis have been introduced in the thesis; then the scattering parameter (S parameter) theory in the frequency domain signal integrity analysis has been presented, as well as the mixed-mode S parameter theory which has developed on the basis of the traditional S parameter theory and facilitate to analyze differential network; the network characteristics of mixed-mode S parameter have been studied in detail. The influence of the reference plane's movement for mixed-mode S parameter and the calculation of the mixed-mode S parameter of cascade network have also been researched. For the first time, a calculation method (using signal flow diagram)for cascaded network'mixed-mode S parameter has been proposed and the calculation formulas have been deduced. Compared with the method of using mixed-mode T parameters, the proposed method is more concise, because it omitted twice conversions between mixed-mode T parameter and mixed-mode S parameter. By the use of the full wave electromagnetic simulation software, the cascade of two parallel differential lines and two differential lines with corners have been modeled and stimulated respectively. By this way, we have verified the correctness of the above-mentioned method. Finally, various discontinuities of differential interconnection in the High-speed interconnection design such as imperfect reference plane, corner and via etc. have been modeled, simulated and analyzed through the full wave electromagnetic simulation software, the mixed-mode S parameters of these discontinuous structure have been achieved, and then the influences of the above mentioned discontinuous structure's parameters for differential signal transmission have been analyzed. The result of the analysis has some usage for solving the signal integrity problems caused by the discontinuities of the High speed differential interconnection.