Leo Raimondo

A Simple and Efficient Design Procedure for Planar Electromagnetic Bandgap Structures on Printed Circuit Boards

In this paper, a simple synthesis procedure to design planar electromagnetic bandgap (EBG) structures is proposed. It is based on the consideration of the excess of inductance of a patterned plane with respect to a solid one. The planar EBG structure is sized from the bandgap starting and ending frequencies, and few others specifications employing a closed form formulation. The proposed method is also suitable for the design of embedded planar EBG. The procedure is validated by using measured and numerically computed results.

Compact Configuration for Common Mode Filter Design based on Planar Electromagnetic Bandgap Structures

A planar electromagnetic bandgap configuration of a compact common mode filter that is laid out on printed circuit board is studied. This filter is used to mitigate the common mode noise traveling on high-speed differential signal traces. These differential signal lines may be connected to I/O connectors and cables and small amounts of common mode noise can result in significant electromagnetic emissions. The filter is obtained by a very simple planar geometry based on the electromagnetic bandgap structures. A cavity made by a rectangular/square patch (together with a solid plane underneath) has a well known and predictable resonant behavior; the coupling between the differential pair routed on top of the patterned plane and the patch cavity, occurring when the traces cross the gap between adjacent patches, is used to reduce the energy associated with the propagation of the common mode noise. The properties of this filter are studied taking into account the layout of a real differential microstrip and the number of gap crossings. A compact configuration is proposed. Time domain simulations validate the suggested layout approach.

IR-DROP Analysis and Thermal Assessment of Planar Electromagnetic Bandgap Structures for Power Integrity Applications

This paper investigates the relationship among the high-frequency performances of a planar electromagnetic bandgap structure for power integrity applications and its static (dc) behavior. The IR-Drop and the thermal performances are accurately investigated through 3-D simulations. Measurements of the high-frequency electromagnetic properties and of the temperature variation are also performed for validating the models employed in the analysis.

Common mode filtering performances of planar EBG structures

This paper approaches the filtering behavior of Electromagnetic Bandgap (EBG) structures. The transfer function, in terms of S-parameters, of a single ended and a differential microstrip line referenced to an EBG plane are considered: the notches (causing signal attenuation) and flat regions (causing signal propagation) are related to the geometry and characteristics of the EBG structure and can be designed to filter out unwanted harmonic components of the signal. A different EBG-like structure is proposed and its performances analyzed.

Design of a Common Mode Filter by Using Planar Electromagnetic Bandgap Structures

In this paper, an embedded electromagnetic bandgap structure is proposed for harmonic filtering of differential signals undesired common mode components. Rather than use lumped circuit components and likely causing some degradation to the intended high speed differential signal, the embedded planar common mode filter causes no degradation to the intended signal, and enhances the signal integrity and electromagnetic compatibility performance of the system. Single ended and differential traces are considered and the impact of the common mode filtering is measured in terms of mixed mode scattering parameters and eye diagram metrics. The systematic procedure to design such a structure is outlined, and its design robustness is also verified.

Fundamental mechanisms of coupling between planar electromagnetic bandgap structures and interconnects in high-speed digital circuits. Part I - microstrip lines

The paper studies the signal integrity performances of a microstripline routed over a planar EBG structure. The fundamental mechanisms of the coupling between the signal transmitted along the trace and the resonant properties of the same structure are investigated.

Advanced Models for Signal Integrity and Electromagnetic Compatibility-Oriented Analysis of Nanointerconnects

This paper presents a new methodology for the transient analysis of nanointerconnects, modeled as lossy and dispersive multiconductor transmission lines. The proposed model is derived from the solution of the Telegraphers equations in the framework of the Sturm-Liouville theory. The open-ended impedance matrix is expressed in a series form as a sum of infinite rational functions, derived by the series form of the Greens function. Hence, a pole-residue rational model can be synthesized and a reduced-order model to be generated by a simple selection of dominant poles. The spectral form of the Greens function also allows to generate a rational model for the transient voltage sensitivity as well. The numerical results confirm the robustness of the proposed technique and its suitability to be adopted in the design flow of next generation nanointerconnects for signal integrity and electromagnetic compatibility purposes.

Experimental validation of common-mode filtering performances of planar electromagnetic band-gap structures

An experimental validation of an electromagnetic band-gap (EBG) based common mode filter is given in this paper. The proposed layout technique is based on planar EBG structures altered by removing the connecting bridges between adjacent patches. The patches are properly dimensioned for ensuring the presence of frequency notches at the frequencies that should be filtered in the common-mode transfer function. The notch frequency is associated with the first resonant mode of the patch.

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.

Routing strategies for improving common mode filter performances in high speed digital differential interconnects

The propagation of the common mode noise on high speed differential traces has an impact on EMI and crosstalk toward nearby traces and electronic devices. A common mode filter, based on a simple planar electromagnetic bandgap, can be easily designed for filtering well-defined harmonics of the propagating common mode signal. The common mode portion of the signal can be reduced through the coupling to the electromagnetic bandgap cavity. This phenomena is obtained at the gap in the reference layer between two adjacent cavities. The electromagnetic principles are introduced and a systematic analysis is carried out in this work investigating the filter performances. The effect of the number of gap crossings on the depth of the filtering band is investigated and a compact layout configuration is introduced for saving layout area.