A simple finite-difference frequency-domain (FDFD) algorithm for analysis of switching noise in printed circuit boards and packages

Simultaneous switching noise (SSN) compromises the integrity of the power distribution structure on multilayer printed circuit boards (PCB). Several methods have been used to investigate SSN. These methods ranged from simple lumped circuit models to full-wave (dynamic) three-dimensional Maxwell equations simulators. In this work, we present an efficient and simple finite-difference frequency-domain (FDFD) based algorithm that can simulate, with high accuracy, the capacity of a PCB board to introduce SSN. The FDFD code developed here also allows for simulation of real-world decoupling capacitors that are typically used to mitigate SSN effects at sub 1 GHz frequencies. Furthermore, the algorithm is capable of including lumped circuit elements having user-specified complex impedance. Numerical results are presented for several test boards and packages, with and without decoupling capacitors. Validation of the FDFD code is demonstrated through comparison with other algorithms and laboratory measurements.     

Design and Analysis of Ultra-Miniaturized Meandering Photonic Crystals Delay Lines

In this paper, we study the characteristics of a novel miniaturized optical delay line, which delays light in a meandering photonic crystal waveguide, and describe the design steps. We show how lattice parameters and refractive index difference of the photonic crystal affect the bandgap width and suggest a criterion to select these parameters. Next, we focus on the parallel waveguide channels in photonic crystal, and analyze the impact of the channel length and the interchannel spacing on crosstalk. We suggest a method for mitering the sharp corners in meandering lines which reduces the undesired reflections by 8 dB. Considering all these guidelines, we examine the propagation of light in the proposed delay line through calculating time-delay and insertion loss. To achieve longer delays in a small device area, we concentrate on coupled cavities in photonic crystals and propose an approximate method for calculating the group velocity of light in the coupled defects. We show how by replacing waveguide channels of a meandering delay line with coupled defects we achieve time-delays more than 9 ps within a device size around 27 m, which corresponds to a miniaturization factor of 100.     

Design of a matching network for an HF antenna using the realfrequency method

The real frequency method (RFM) is used to design a matching network for an electrically short loaded dipole. The RFM is demonstrated to be superior to other analytical and numerical techniques in the sense that it yields the maximum flat transducer power gain possible, and that it does not require any analytical modeling of the load impedance to be matched. For this reason, the RFM is found to be well suited for matching distributed systems such as antennas     

The complementary derivatives method: a second-order accurate interpolation scheme for non-uniform grid in FDTD simulation

Non-uniform grid in finite-difference time-domain methods, which is typically used to resolve fine structures, can reduce the computational domain and therefore lead to a reduction of the computational cost. However, for high-accuracy problems, such as partially-filled parallel plate waveguide and resonators, using different grid size increases the truncation error at the boundary of domains having different grid size. To address this problem, in this work, we introduce the complementary derivatives method (CDM). Theoretical discussion and numerical results will be presented to show that the CDM can maintain second-order accuracy throughout the computational domain.     

Surface Finish Effects on High-Speed Signal Degradation

In high-speed circuits, skin effects and dielectric properties are important factors for signal degradation considerations, especially in the microwave frequency region. When surface finishes are applied to prevent traces from oxidation, the electrical properties of traces are affected. In this work, experimental study and finite element method (FEM) based full wave simulation are used to investigate the effects of hot air solder leveling (HASL) and its alternatives on signal integrity. Classical interconnect structures, microstrip line, and differential mode coupled microstrip lines subjected to different finishes are investigated. Our work reveals that the net conductor loss that results from surface finishes is the dominant factor in signal degradation when the clock frequency is within the microwave frequency region. For microstrip line, the influence of surface finishes on signal distortion is negligible; for differential mode coupled microstrip lines, however, the surface finish effects, especially those with high resistivity, can lead to significant signal distortions. These findings are expected to have strong implications when designing high-speed circuits that meet strict timing requirements.     

Modeling of magnetostatic resonances in small-size metamaterials

This work studies the resonant behavior of nanoscale magnetic materials. This behavior, henceforth referred to as magnetostatic resonance, occurs at frequencies where the permeability is negative and the particle is much smaller than the wavelength. A surface integral equation is formulated on the boundary of the particle to calculate the resonance frequencies and modes. Unique physical properties of these resonances such as scale invariance of resonance frequency and orthogonality properties of resonant modes are studied. A numerical technique is presented to calculate the magnetostatic resonance frequencies of an arbitrary shape. Possible applications of these phenomena are outlined.     

Simultaneous switching noise mitigation in PCB using cascaded high-impedance surfaces

A novel concept for ultra-wide-bandwidth suppression of simultaneous switching noise (SSN) in high-speed printed circuit boards (PCBs) is proposed and implemented. This method consists of cascading high-impedance surfaces (HIS) with different stop bands, creating rejection over a wide frequency region. A PCB with the cascaded HIS design has been successfully fabricated and tested.     

Novel Planar Electromagnetic Bandgap Structures for Mitigation of Switching Noise and EMI Reduction in High-Speed Circuits

Planar electromagnetic bandgap (EBG) structures with novel meandered lines and super cell configuration are proposed for mitigating simultaneous switching noise propagation in high-speed printed circuit boards. An ultrawide bandgap extending from 250 MHz to 12 GHz and beyond is demonstrated by both simulation and measurement, and a good agreement is observed. These perforated EBG-based power planes may cause spurious and unwanted radiation. In this paper, leakage radiation through these imperfect planes is carefully investigated. It is found that the leakage field from these planar EBG structures is highly concentrated around the feed point, and the field intensity is attenuated dramatically when passing across several periods of patches. A novel concept of using these EBG structures for electromagnetic interference reduction is also introduced. Finally, the impact of power plane with EBG-patterned structures on signal integrity is studied.     

Frequency-domain complementary operators for finite-elementssimulation

A new mesh-truncation technique is introduced for the frequency-domain (time-harmonic) solution of open-region radiation problems. The technique is based on the complementary operators method (COM), where two independent solutions are averaged to eliminate first-order boundary reflections. The dual complementariness in the frequency domain is achieved by introducing a discrete-domain operator that achieves the objective of ∂_t in the original time-domain development of COM     

<Emphasis Type="Italic">n</Emphasis>th order Rose curve as a generic candidate for RF artificial magnetic material

Recent work demonstrated that the permeability and magnetic loss tangent of artificial magnetic material inclusions can be represented simply in terms of the circumference and area of the inclusion. While such a representation makes direct use of the inclusion’s circuit model, the fact that the magnetic properties can be described in terms of the perimeter and area of the inclusion facilitates designing inclusions that achieve specific constraints without the need for intensive full-wave trial and error simulations. Because of such flexibility, we propose a new set of generic curves described as nth order Rose curves to be candidates for AMMs. In fact, the new curves not only provide significant design flexibility, but provide features not present in traditional topologies, most pronouncedly a wider band over which negative permeability is achieved with low dispersion.