Francesco de Paulis

Signal/Power Integrity Analysis for Multilayer Printed Circuit Boards Using Cascaded S-Parameters

A cascaded S-parameter method is proposed in this paper for signal/power integrity analysis of multiple vias in a multilayer printed circuit board (PCB). The proposed method enables efficient and accurate construction and simulation of physics-based via model for complex multilayer PCB structures involving vias. The physics-based via model describes the parasitic effects near each via region as well as mutual coupling among different vias. In this model, each via portion between two parallel plates is regarded as a three-port network with two coaxial ports and one radial port between the two plates. A procedure is first developed to obtain the S-parameters of a single plate pair, which combine the three-port via networks with the impedance matrix of the parallel-plate pair. Once the S-parameters of each plate pair are obtained, an assembling technique for cascading microwave networks is further developed. The method proposed in this paper has been validated by both simulations with a commercial circuit simulator and measurements.

Transient Analysis of TSV Equivalent Circuit Considering Nonlinear MOS Capacitance Effects

An equivalent circuit model for the transient analysis of through-silicon vias (TSV) taking into account nonlinear metal-oxide-semiconductor effects is proposed. The model takes into account the nonlinear behavior of the doped silicon substrate in presence of the electric potential difference due to the transient voltage between the TSVs. The impact of time-variant capacitance between the via and the substrate on crosstalk and signal propagation is analyzed.

Accurate and Efficient Analysis of Planar Electromagnetic Band-Gap Structures for Power Bus Noise Mitigation in the GHz Band

Noise reduction in PCB is a major concern in the present digital electronic systems with data rate beyond 10Gbps. The noise, due to simultaneous switching noise, radiation from signal vias crossing the planes, etc. can propagate within parallel plane cavity at its resonant frequencies, thus allowing coupling between integrated circuits (ICs) far from each other. Electromagnetic band-gap (EBG) structures are largely employed as noise reduction technique. This paper presents a quick and e-cient analytical approach for evaluating the EBG noise reduction performances in terms of band-gap limits. The study is based on the physics behavior of the planar EBG structures, focusing on its resonant properties. The resonant modes of the EBG cavity are afiected by the additional inductance of the patterned plane respect to the case of the ideal solid plane cavity. The formulas provided, based on the quantiflcation of such inductance, can be easily implemented and employed for a quick layout design of power planes in multilayer PCBs, as shown in a practical example of a partial EBG plane.

Optimum geometrical parameters for the EBG-based common mode filter design

This paper presents an efficient design procedure to obtain the physical dimensions of the electromagnetic bandgap (EBG) structure intended to filter common mode noise in high speed differential interconnects. The procedure is based on the concept of total inductance associated to the EBG geometry, and it offers wide flexibility for setting the geometrical EBG parameters. An optimum EBG design is studied investigating the relationships among the design parameters. This allows restricting the range of parameters that minimize the error between the achieved filter frequency and the nominal frequency. The study is carried out for several filtering frequency values and the results are validated by using full wave simulations. This paper also offers an example to synthesize the optimum EBG design for achieving a common mode filter at the desired frequency.

EBG-Based Common-Mode Microstrip and Stripline Filters: Experimental Investigation of Performances and Crosstalk

The aim of this study is to analyze from a modeling and experimental point of view the filter effectiveness and the crosstalk among signal traces crossing the same common-mode filter based on electromagnetic bandgap structures in a modern server design configurations. Both microstrips and striplines are considered in the study, detailing the differences among them in the design step as well as in filter geometry and response. Simulation models and experimental setups are carefully described, and the numerical and measurement results are compared and discussed.

Design of Homogeneous and Composite Materials From Shielding Effectiveness Specifications

A procedure to synthesize a suitable biphasic composite material from the given Shielding effectiveness (SE) specifications is proposed herein. In particular, this paper presents an analytic approach for calculating parameters of a Debye-like equivalent homogeneous material, which meets the SE requirements in given frequency range. Establishing the relationship of the SE with the intrinsic material and morphological properties of a composite will make it possible to effectively find an equivalent homogeneous lossy Debye-like material model, starting from the given SE frequency characteristic. The Maxwell Garnett mixing rule is used to synthesize a composite made by aligned cylindrical inclusions. A few examples of how this procedure works are presented; validation by time domain numerical simulations is provided.

Impact of Frequency-Dependent and Nonlinear Parameters on Transient Analysis of Through Silicon Vias Equivalent Circuit

This paper introduces an equivalent circuit model for through silicon vias including the nonlinear effect of metal-oxide-semiconductor capacitance. This nonlinear effect is combined to the frequency-dependent via resistance and inductance, as well as capacitance and conductance of the silicon substrate for a transient analysis. The impact of frequency-dependent RLCG parameters and the nonlinear depletion capacitance on signal propagation, crosstalk and eye diagram is studied using the proposed equivalent circuit model.

Removable EBG-Based Common-Mode Filter for High-Speed Signaling: Experimental Validation of Prototype Design

A new common-mode filter structure based on planar electromagnetic bandgap (EBG) technologies is designed, fabricated, and measured. It is based on a previously proposed geometry, implementing a sequence of two or more EBGs resonating at a filtering frequency; however, the new filter is placed on the top of the PCB as a standalone component, instead of being included within the PCB stack up. The filter can be easily removed and substituted by another one that is designed to filter a different frequency. The replacement design should maintain the same external size of the component as the original filter, which can be achieved by choosing the permittivity of the dielectric as well as the relationship among the EBG parameters appropriately. The electromagnetic behavior of the filter is simulated and a prototype structure is fabricated and measured. Results are compared to validate the design concept and procedure.

Equivalent circuit models for evaluation of bandgap limits for planar electromagnetic bandgap structures

In this work different physic based equivalent lumped element circuits models representing planar EBG structures are developed. Their results, in terms of evaluation of the lower and upper limits of the bandgap, are compared with a three dimensional simulation considered as reference. Guidelines for the use of these models for their use in planar EBG design are developed.

Equivalent Circuit Modeling of Dielectric Hysteresis Loops in Through Silicon Vias

This paper proposes a numerical solution of the nonlinear equations that describes the hysteretic behavior of the coupling capacitance among through silicon vias in three-dimensional integrated circuits. Behavioral ordinary differential equations are formulated and solved by an equivalent circuit described in SPICE syntax. These results are then compared with those obtained by measurements.