There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

This paper reviews recent progress and future directions of signal integrity design for high-speed digital circuits, focusing on four areas: signal propagation on transmission lines, discontinuity modeling and characterization, measurement techniques, and link-path design and analysis.

Signal Integrity Design for High-Speed Digital Circuits: Progress and Directions

Mitigating power distribution network (PDN) noise is one of the main efforts for power integrity (PI) design in high-speed or mixed-signal circuits. Possible solutions, which are based on decoupling or isolation concept, for suppressing PDN noise on package or printed circuit board (PCB) levels are reviewed in this paper. Keeping the PDN impedance very low in a wide frequency range, except at dc, by employing a shunt capacitors, which can be in-chip, package, or PCB levels, is the first priority way for PI design. The decoupling techniques including the planes structure, surface-mounted technology decoupling capacitors, and embedded capacitors will be discussed. The isolation approach that keeps part of the PDN at high impedance is another way to reduce the PDN noise propagation. Besides the typical isolation approaches such as the etched slots and filter, the new isolation concept using electromagnetic bandgap structures will also be discussed.

Overview of Power Integrity Solutions on Package and PCB: Decoupling and EBG Isolation

The ever-increasing demands of digital computing and wireless communication have been driving the semiconductor technology to change with each passing day. Modern electronic systems integrate more complex components and devices, which results in a very complex electromagnetic (EM) field environment. EM compatibility has become one of the major issues in ICs redesign, mainly due to the lack of efficient and accurate simulation tools and expertise on noise reduction and immunity improvement. This paper reviews the state of the arts of IC, electronic package, and printed circuit board simulation and modeling technologies. It summarizes the modeling technologies for both available structures [multilayered power-ground planes and macromodeling of interconnect (INC)] and novel structures (nano-INCs and 3-D ICs based on through-silicon via technology). It also illustrates the trends of simulation and modeling technologies in EM compatibility, signal integrity, and power integrity.

Progress Review of Electromagnetic Compatibility Analysis Technologies for Packages, Printed Circuit Boards, and Novel Interconnects

Advanced packaging

The First Comprehensive, Example-Rich Guide to Power Integrity ModelingProfessionals such as signal integrity engineers, package designers, and system architects need to thoroughly understand signal and power integrity issues in order to successfully design packages and boards for high speed systems Now, for the first time, there's a complete guide to power integrity modeling: everything you need to know, from the basics through the state of the artUsing realistic case studies and downloadable software examples, two leading experts demonstrate today's best techniques for designing and modeling interconnects to efficiently distribute power and minimize noiseThe authors carefully introduce the core concepts of power distribution design, systematically present and compare leading techniques for modeling noise, and link these techniques to specific applications Their many examples range from the simplest (using analytical equations to compute power supply noise) through complex system-level applicationsThe authors Introduce power delivery network components, analysis, high-frequency measurement, and modeling requirements Thoroughly explain modeling of power/ground planes, including plane behavior, lumped modeling, distributed circuit-based approaches, and much more Offer in-depth coverage of simultaneous switching noise, including modeling for return currents using time- and frequency-domain analysis Introduce several leading time-domain simulation methods, such as macromodeling, and discuss their advantages and disadvantages Present the application of the modeling methods on several advanced case studies that include high-speed servers, high-speed differential signaling, chip package analysis, materials characterization, embedded decoupling capacitors, and electromagnetic bandgap structures This book's system-level focus and practical examples will make it indispensable for every student and professional concerned with power integrity, including electrical engineers, system designers, signal integrity engineers, and materials scientists It will also be valuable to developers building software that helps to analyze high-speed systems

Power Integrity Modeling and Design for Semiconductors and Systems

Power/ground planes in electronic packaging can be a major factor for noise coupling. There can be noise coupling not only in the transversal direction between two planes, but also vertically from one plane pair to another through the apertures and via holes. Due to the large size of the power/ground planes, it is difficult to analyze them using full-wave simulators. It is known that the finite-difference solution of the Helmholtz equation provides a faster approach with comparable accuracy. For multilayered planes and arbitrary geometries with aperture coupling, we present a multilayered finite-difference method (MFDM). It provides an accurate representation of wrap-around currents, which have not been modeled earlier, for large cutouts. Estimation of the influence of such coupling effects are essential especially for a successful design of mixed-signal systems. This method allows to consider realistic structures, which would be prohibitive to simulate using full-wave simulators.

Multilayered Finite-Difference Method (MFDM) for Modeling of Package and Printed Circuit Board Planes

A major bottleneck in high-speed signaling is the simultaneous switching noise (SSN), which is caused by simultaneously switching output buffers. SSN is a result of the coupling between the signal lines and the power delivery network (PDN) in off-chip signaling. This coupling occurs at discontinuities of the transmission line, wherever there is an interruption of the current return path. A particular location where there is a return path discontinuity is the output buffer that is connected to a transmission line. To reduce this discontinuity, current designs try to maintain a low- impedance PDN for the I/O lines up to the output buffers on the chip. This requires a complicated design of the package and interconnections using, for example, planes for the PDN and decoupling capacitors on the package. For GHz signaling, it can be very difficult to maintain sufficiently low impedance. This paper presents a new PDN design, called as the power transmission line, which overcomes these problems.

Power transmission lines: A new interconnect design to eliminate simultaneous switching noise

Size reduction of an electromagnetic bandgap (EBG) structure with large patches and small branches that connect adjacent patches for a power/ground plane pair is studied. To shrink the dimensions with a high isolation at the frequency of interest, this paper provides two approaches. One is a geometric approach which is to place two narrow slits on each patch. The increase of branch inductance with the long slit successfully decreases the on-set frequency of the stopband without increasing the patch size. The other approach is to use high-K material for a thin dielectric layer. In this case, the size reduction can be predicted according to a scaling law. These approaches are applied together to realize an EBG structure with the entire size of less than 20 mm on a side. It covers the GSM band with sufficient isolation. Through this study, the dispersion-diagram analysis is used to predict the stopband characteristics.

http://www2.ece.gatech.edu/research/labs/hppdl/Epsilon2010/publications/2006/01645901.pdf

Size reduction of electromagnetic bandgap (EBG) structures with new geometries and materials

Electromagnetic bandgap (EBG) structures that provide an excellent isolation within the stopband are extremely effective in suppressing propagation of simultaneous switching noise on parallel power planes. However, a scattering parameter measurement and full-wave electromagnetic simulation for their entire structure are costly and time consuming. This letter presents a two-dimensional dispersion-diagram analysis based on a unit-cell network of EBG structures by extending a well-known dispersion-diagram analysis of one-dimensional infinite periodic structures. The approach is extremely effective in computing stopband frequencies and provides the stopbands with good agreement to the measured results

A.E. Engin

Papers

Power Integrity Modeling and Design for Semiconductors and Systems

Multilayered Finite-Difference Method (MFDM) for Modeling of Package and Printed Circuit Board Planes

Power transmission lines: A new interconnect design to eliminate simultaneous switching noise

Size reduction of electromagnetic bandgap (EBG) structures with new geometries and materials

Stopband Analysis Using Dispersion Diagram for Two-Dimensional Electromagnetic Bandgap Structures in Printed Circuit Boards