Electromagnetic modeling and signal integrity simulation of power/ground networks in high speed digital packages and printed circuit boards

Abstract

The electromagnetic modeling and parameter extraction of digital packages and PCB boards for system signal integrity applications are presented. A systematic approach to analyze complex power/ ground structures and simulate their effects on digital systems is developed. First, an integral equation boundary element algorithm is applied to the electromagnetic modeling of the PCB structures. Then, equivalent circuits of the power/ground networks are extracted from the EM solution. In an integrated simulation scheme, the equivalent circuits are combined with signal nets, package models, device circuits, and other external circuitry for system level signal integrity analysis and simulation. This methodology has been implemented as software tools and applied to practical design problems. Effects related to power/ground networks, such as simultaneous switching noises, crosstalk, and ground discontinuity are analyzed for realistic designs. INTRODUCTIONWith the ever increasing speed and density of digital integrated circuit systems, effects due to field interaction among IC chips, packages and PCB boards have become more and more the limiting factors in high speed system design [1][2][3]. Signal integrity effects such as propagation delay, crosstalk, and simultaneous switching noises (SSN) require more accurate and efficient electromagnetic analysis and modeling beyond the traditional static method with a few lumped circuit elements. Particularly, the power/ground supply networks in digital circuits involve complex, large structures such as combinations of plane/partial planes and routed traces in multilayer environment, and are often tightly coupled with other parts of the circuit systems, such as signal networks and chip packages. Characterization of true distributed effect and frequency dependence is crucial. On the other hand, due to the overwhelming complexity of digital circuit board, full-wave rigorous electromagnetic field solutions, such as those used in microwave analysis [4], become impractical for digital application because of the extremely high computational requirement, and the difficulty of integrating with time-domain circuit type simulators and design environments used by digital designers. Therefore, EM modeling and simulation methodologies that can handle large complex digital designs with reasonable accuracy and efficiency, and can provide good macro models over extended frequency bands, are very much desired and thus present a challenge to us [5][6][7][8].This paper presents a systematic approach which includes an efficient method for the electromagnetic modeling of packages and power/ground structures, and an integrated process for the analysis and simulation of system signal integrity and SSN effect in practical digital designs. The focus of this work is to develop a fast, flexible and accurate electromagnetic model with a clear circuit interpretation for the power/ground network, and to integrate it with active device models, transmission line networks, and chip package parasitics in a ti...

Quantifying SMT decoupling capacitor placement in dc power-bus design for multilayer PCBs

“…Full-wave electromagnetic modeling approaches such as MoM, FEM, and FDTD can be used for dc power-bus modeling [22], [23]. However, a circuit type of simulation is, more often, desirable for PCB-related signal integrity (SI) and electromagnetic interference (EMI) modeling [24]- [26], since it is very compatible with digital device and transmission line models. The CEMPIE approach is a dc power-bus modeling method with circuit extraction, and is an application of the partial element equivalent circuit (PEEC) approach for general multilayer dielectric media [27], [28].…”

Stitching a Reference Plane Split Using Routing Layer Traces to Improve I/O Bus Signal Integrity

“…As the number of power supply rails increased dramatically in desktop and mobile systems, multiple power planes on a real estate constraint platform often forces high speed interfaces to cross different reference planes. It is a known fact that when high speed transmission lines cross a reference plan split, cross coupling and radiated emission are greatly increased [1][2][3][4][5]. Increased cross coupling leads to greater-than-expected signal quality degradation, and on critical interfaces, have been known to cause signaling failures.…”