Analysis Of Signal Integrity In High Speed PCB Design

In the pursuit of higher performance of electronic products, the semiconductor technology constantly develop and the signal frequency constantly improve.Signal rise or fall time are therefore continuously shortened, resulting in signal integrity problems.For example,transmission line signal reflection, crosstalk,ect. These problems,seriously affecting the stable operation of the circuit, cause great distress to the hardware engineer. The traditional "design- manufacture- verify and analysis- modify" design method has been unable to meet the increasingly complex design requirements,furthermore, faster product updates period and cost control requirements, put forward higher requirements for our hardware designer. We were in the PCB(Printed Circuit Board) design, have to consider how to transmit signal better in the printed circuit board without distortion. Therefore, we need to consider the impact of signal integrity on the circuit at the beginning of the design, taking appropriate measures, to eliminate the influence.In this paper, aiming at the above problems, we study common phenomenons of signal integrity, analysis of the causes of these phenomenons, and gives the solution to the problem. Analysis of the basic structure of printed circuit board, summarizes how to better control the printed line impedance, and emphatically probes into the via.Introduces the development of IBIS specification and the structure of IBIS model, and also introduces the basic content of the simulation tool ‘Cadence’. Combined with the actual project,I explore the application of simulation technology in PCB design,and finish the simulation of reflection and crosstalk.Then we complete the PCB design according to the simulation results. Finally, the real signal is measured. The main contents of this article is:1. Firstly, this paper introduces the basic knowledge of the transmission line theory.2. Then introduce the signal integrity problems.Signal reflection and crosstalk of transmission line is studied.Analysis of signal reflection suppression in different terminal matching; analysis of the impact of attacks signal line on adjacent signal line,giving out how to reduce the signal crosstalk between transmission lines. According tothe common rail collapse problem, its causes are discussed. We discuss the common method to solving the rail collapse problem-- using the decoupling capacitor. We also discuss the problem of EMI in PCB design.3. This paper introduces the basic structure of printed circuit board and the impedance control of the PCB. Especifically, the via of PCB are analyzed and discussed.Then we conclude the rules that PCB signal integrity design should follow.4. At present, IBIS(I/O BufferInformation Specification) model is more and more willing to accept by the device manufactures and most manufacturers provide IBIS model of device. This paper analyzes the structure of IBIS model, introduces the application of IBIS model in EDA simulation.5. In view of the current several popular simulation software tools, I chose the simulation tool of Cadence research. Through the actual case simulation of reflection and crosstalk,I give the rule the PCB designer should conform to.After the PCB design,I finish the post layout simulation.Finally, the actual measurement result is gived out.