Power Integrity In High-speed Circuit Study

With the continuous development in communication electronics of mobile system and computer chip, the speed and scale of integrated circuit (IC) chip increase rapidly and cause a series of high-frequency problems such as signal integrity, power consumption, electromagnetic interference and so on. Due to the trend towards low voltage and low power signaling in mobile systems, power supply can be a major bottleneck for reliable functioning of the systems. The power/ground bounce, also named as simultaneous switching noise (SSN) or Delta-I noise affects circuit performance seriously. In order to analyze the time or frequency response of the power/ground structure, electromagnetic modeling has to be made, which plays an important role in the design stage of electronic system. It is the foundation of the following work. The subject of this dissertation is electromagnetic modeling and corresponding method study of power/ground stucture in high speed integrated circuits. This dissertation has made the following researches: 1.On the basis of finite-difference time-domain (FDTD) method, an unconditionally stable finite-difference time-domain (US-FDTD) method with weighted Laguerre polynomials is studied and extended to three-dimensional electromagnetic problems. The US-FDTD method is not limited by the well-known Courant-Friedrich-Lecy (CFL) stability condition, and this marching-on-in-order method does not utilize the explicit leapfrog time scheme of conventional FDTD method and can efficiently solve problems with fine interconnect and packaging structures. 2. For simultaneous switching noise (SSN) problems in high speed integrated circuits, typical models of power/ground structures are extracted with through-hole vias being taken into account. Moreover, SSN and properties of impedance are analyzed in the cases of power/ground structure truncated by different boundary conditions. 3. The US-FDTD algorithm is applied to analyzing the SSN and impedance of power/ground structures. Combined with graded mesh partitioning technique, the computation burden is tremendously cut down and the simulation efficiency is greatly enhanced. Fortran programs have been developed for all above approaches and some work has been done in software development.