Kazuhide Uriu

Stopband prediction with dispersion diagram for electromagnetic bandgap structures in printed circuit boards

Electromagnetic bandgap (EBG) structures that prevent propagation of electromagnetic waves within a given frequency range are quite effective in suppressing simultaneous switching noise on parallel power planes. However, it is quite time consuming to compute the stopband frequencies of interest using full-wave electromagnetic simulation of the entire structure. In contrast, using dispersion-diagram analysis based on a unit- cell network of EBG structures is more efficient and less time consuming. This paper presents an approach for two-dimensional EBG structures by extending a well-known dispersion-diagram analysis of one-dimensional infinite periodic structures. The stopbands predicted with the proposed analysis were compared with good agreement to measured and simulated results. In addition, the concept was applied to test the stopband range of EBG structures formed on an actual printed circuit board with a test coupon of an EBG unit cell placed on the same board.

Efficient Modeling of Package Power Delivery Networks with Fringing Fields and Gap Coupling in Mixed Signal Systems

Full-wave EM simulations are computationally expensive given the complexity of packaging structures in modern mixed signal systems. Fast methods such as the transmission matrix method are inaccurate as they do not model discontinuities such as metal edges and gaps. In this paper, simple models for the edge effect and gap coupling are developed for the finite difference frequency domain method. Results are presented comparing the accuracy of the proposed method with full-wave simulations and measurements

Noise induced jitter in differential signaling

Differential lines are extensively used in high-speed digital circuits due to their ability to improve signal integrity by rejecting common-mode noise. However noise is injected into differential signals when there are irregularities in the signaling setup. These anomalies may be via transitions of differential lines through power planes in power distribution systems, via stubs, asymmetric lengths of differential lines, different transition points for each of the differential vias etc. This paper quantifies noise due to irregular differential structures in frequency domain. Presence of noise in differential signaling is verified through a set of test vehicles. The effect of signal to power coupling from differential lines on signal jitter is also investigated.

Signal and Power Integrity Co-Simulation for Multi-layered System on Package Modules

The coupling of simultaneous switching noise (SSN) in mixed signal system on package modules is a critical signal and power integrity (SI/PI) problem. In the presence of split planes and apertures, SSN coupling occurs both horizontally as well as vertically across layers. Thus, to catch SI and PI problems at an early stage of design requires fast signal and power co-simulation methodologies. In this paper, we outline the multi-layer finite difference method and how the accuracy of the technique can be enhanced with models for fringe and gap effects. We then briefly describe a method for integrating the signal distribution network with the power distribution network to enable co-simulation. The method is then applied to a mixed signal board containing split planes, and numerical results are compared to full-wave simulations.

Computationally efficient power integrity simulation for system-on-package applications

Power integrity simulation for system-on-package (SoP) based modules is a crucial bottleneck in the SoP design flow. In this paper, the multi-layer finite difference method (M-FDM) augmented with models for split planes has been proposed as a fast and accurate frequency domain engine. Results demonstrating the accuracy and scalability of the method have been presented. In particular, the algorithm was employed to the analysis of a realistic 6 layer package with ~ 200k nodes.

Efficient Simulation of Power/Ground Planes for SiP Applications

Packages for modern mixed signal systems in package (SiP) require split planes and power islands to isolate multiple power supplies. To reduce design iterations due to signal integrity issues, the frequency response of the package needs to be obtained accurately at an early stage of the design. Full-wave EM solvers are generally the most accurate tools available. However, the high time and memory required by such tools relegates their use to final verification, at which stage design iterations are expensive. The finite difference method has been shown to be efficient in simulating single plane-pair structures with slots as long as one plane is completely solid. Also, the multilayer finite difference method (M-FDM) can accurately model multilayer structures with apertures, so long as there are no power islands. In this paper, a formulation for efficient simulation of multilayer structures with split planes has been investigated. Further, a method by which transmission lines can be integrated with a power distribution network containing apertures and split planes has been discussed. The formulation has been validated by comparing results with full-wave EM simulations.

Suppression of anti-resonance peaks by controlling off-chip damping parameters

Simultaneous switching noise (SSN) is a serious design issue to stabilize power supply integrity and logic operation in advanced CMOS circuits and systems. Furthermore, SSN causes electromagnetic interference (EMI). Ringing frequency observed in the SSN waveforms is strongly related to the anti-resonance peak frequency of the total PDN impedance. Therefore, suppressing the anti-resonance peak is currently one of the most important design concerns in VLSI systems. In this paper, the method which is called “on-board snubber circuits (RC series circuits)” has been studied to suppress the anti-resonance peak. The on-board snubber circuits was added just at the beneath of the power supply terminals of the LSI to effectively suppress the anti-resonance peak of the total PDN impedance. In particular, the design space for damping the anti-resonance peak critically and the added values of capacitance (Csnb) and resistance (Rdmp) of the snubber circuits has been examined.