Research Of Signal Integrity And Electromagnetic Compatibility In High Speed Interconnect Design

Effects of interconnects on the electrical performance of digital components, such as microprocessors, have historically been small enough, and we can handle almost all the problems with simple rules of thumb. However, with the development of technology and the rapid increase of information, people's increasing demands for bandwidth push the continuous enhancement of the speed of microprocessors and buses. There is now processors of several millionhertz to several gigahertz everywhere, furthermore, even higher speed components will emerge in the near future, thus satisfy people's requirement of the real time transfer of data, voice and image.Signal rise/fall time will get short as possible when the speed of digital system increase, while the increase of frequency and edge rate will bring a series of high speed design problems. In today's high speed circuit applications, it is a common practice to observe interconnect problems such as delay, reflection, attenuation, dispersion, crosstalk and ground bounce, etc. These effects may result in significant distortion in pulses that propagate even a short distance. In addition, electromagnetic interference will become prominent along with the increase of edge rate and frequency. Thus, Signal integrity and electromagnetic compatibility during signal propagation turn into the two main problems of modern circuit integration. These problems bring greater challenges to the system hardware design, many correct designs from the logic point of view would tend to fail if not well dealt with during real PCB design. Experts have predicted that the cost of logic design will decrease greatly in the future hardware design, whereas the cost related to high speed design will account for eighty percent or more of the total cost, high speed interconnect design has become the dominant factor of system design.In Chapter 1 , the importance of interconnect design is stated, the classification and model as well as the signal integrity and electromagnetic compatibility problems of high speed interconnect design are introduced, the present research status concluded this chapter.In Chapter 2, the analysis methods concerned with high speed interconnect design are discussed, including the formulation of circuit equations and model reduction algorithm.In Chapter 3, Based on the explanation of the transmission line model, the signal integrity problem is stated, including reflection, crosstalk, SSN and nonideal interconnect, etc. Timing equations which the system must meet is given; the five common used termination methods are simulated using the Cadence PSD 14.2 software package, the influence of variation of some parameters to crosstalk in two coupled transmission lines is analyzed, including spacing, line length, thickness of dielectric layer, frequency and rise time of interfering signal, also, the effects of on-chip and off-chip decoupling capacitor in reducing SSN are analyzed.In Chapter 4, the electromagnetic compatibility problem in high speed interconnect design is studied, the mechanism of electromagnetic radiation and the frequency behaviour of far field differential mode and common mode are stated, theHIeffects of decoupling capacitor, ferrite and common mode choke in the optimization of PDS performance and minimization of EMI are analyzed through software simulation.In Chapter 5, the main work of this dissertation is summarized and the advice of later work is given.