Adjacent Traces Research Articles

Ground Bounce Noise Induced by Crosstalk Noise for Two Parallel Ground Planes With a Narrow Open-Stub Line and Adjacent Signal Traces in Multilayer Package Structure

This paper investigates how ground bounce noise (GBN) is generated by crosstalk noises for two parallel ground planes with a narrow open-stub line (NOSL) and adjacent signal traces in a multilayer package structure. A noise reduction scheme and design guidelines for preventing intense noises (GBN and coupled noise) are also proposed. A graphical method that is based on wave tracing is also developed to elucidate the generation of crosstalk noise by adjacent signal traces on an NOSL. The mechanism of generation of the GBN by crosstalk noise can be elucidated based on reflection theory, open-stub quarter-wavelength resonance, and parallel-plane resonance. The time-domain simulation results are analyzed using a 3-D full-wave simulator, Computer Simulation Technology. Using an additional shorting via at the connection between the NOSL and parallel ground planes, the proposed noise reduction scheme can significantly reduce the GBN and coupled noise. Moreover, guidelines for designing the test structure to minimize noise (GBN and coupled noise) are presented. Finally, the simulation and measurement results in the time domain are compared to validate the proposed analysis and noise reduction scheme.

Power loss in dipping internal reflectors, imaged using ice-penetrating radar

AbstractThe geometry of ice-sheet internal layers is frequently interpreted as an indicator of present and past ice-sheet flow dynamics. One of the primary goals of radio-echo sounding is to accurately reproduce that layer geometry. Internal layers show a loss in reflection amplitude as a function of increasing dip angle. We posit that this energy loss occurs via several mechanisms: destructive interference in trace stacking, energy dispersion through synthetic aperture radar (SAR) processing and off-nadir ray path losses. Adjacent traces collected over a dipping horizon contain reflection arrivals which are not in phase. Stacking these traces results in destructive interference. When the phase shift between adjacent traces exceeds one-half wavelength, SAR processing, which otherwise coherently combines data from dipping reflectors, disperses the energy, reducing image quality further. Along with amplitude loss from destructive stacking and SAR dispersion, imaging reflectors from off-nadir angles results in additional travel time and thus additional englacial attenuation relative to horizontal reflectors at similar depths. When selecting radar frequency, spatial sample rate and stacking interval for a given survey, the geometry of the imaging target must be considered. Based on our analysis, we make survey design recommendations for these parameters.

Non-uniform PCB traces with prescribed frequency bands for improved crosstalk immunity

In this work, a new design approach for realizing printed circuit board (PCB) trace configuration with continuous impedance perturbation to reduce crosstalk in PCB interconnects is investigated. The purpose is to reduce far-end crosstalk without incorporating additional PCB components in order to modify the reactive couplings between the adjacent traces, however at the expense of the available frequency band. This is achieved by replacing a uniform victim trace on a PCB with a continuously varying-impedance trace that exhibits a lowpass filter frequency characteristic. A simplified design approach of the proposed trace impedance profile which is governed by a truncated fourier series is presented. The proposed trace shows better crosstalk reduction results compared to conventional intervening guard trace schemes. Several configurations were designed, implemented, and tested to demonstrate the advantages of the underlying principle.

Velocity versus Offset (VVO) Estimation Using Local Event Correlation and Its Application in Seismic Processing and Analysis

Conventional velocity analysis is usually done in a relatively spare grid, for instance every half kilometers, during the processing of seismic data. It is very laborious work and very subjective. To deliver an accurate velocity picking, processing geophysicists must have a good understanding of geological background of area being analyzed and experiences. Velocity errors often occur during picking. Proper quality control and checking are a must. A good and reliable velocity field is very important in seismic processing for achieving high-quality seismic images as well as for delivering an accurate depth conversion. The new method presented here, was developed to correct velocity errors automatically by means of residual velocity correction, and to produce an offset-dependent RMS velocity field at the same time. The method is data driven, based on the normal move out equation (NMO) and measuring the local even correlation between adjacent traces. The stacking velocity is derived simply by averaging the velocity field. The proposed method was tested on synthetic and real data examples with good result. The velocity field has certain characteristics related to hydrocarbon presence. Supriyono (2011 and 2012) developed a new DHI method using velocity gradient attributes by cross-plotting the velocity versus offset (VVO). The velocity gradient exhibits high anomalous values in the presence of gas.

Noncausal f–x–y regularized nonstationary prediction filtering for random noise attenuation on 3D seismic data

Abstract Seismic noise attenuation is very important for seismic data analysis and interpretation, especially for 3D seismic data. In this paper, we propose a novel method for 3D seismic random noise attenuation by applying noncausal regularized nonstationary autoregression (NRNA) in f–x–y domain. The proposed method, 3D NRNA ( f–x–y domain) is the extended version of 2D NRNA ( f–x domain). f–x–y NRNA can adaptively estimate seismic events of which slopes vary in 3D space. The key idea of this paper is to consider that the central trace can be predicted by all around this trace from all directions in 3D seismic cube, while the 2D f–x NRNA just considers that the middle trace can be predicted by adjacent traces along one space direction. 3D f–x–y NRNA uses more information from circumjacent traces than 2D f–x NRNA to estimate signals. Shaping regularization technology guarantees that the nonstationary autoregression problem can be realizable in mathematics with high computational efficiency. Synthetic and field data examples demonstrate that, compared with f–x NRNA method, f–x–y NRNA can be more effective in suppressing random noise and improve trace-by-trace consistency, which are useful in conjunction with interactive interpretation and auto-picking tools such as automatic event tracking.

Polarization behavior of femtosecond laser written optical waveguides in Ti:Sapphire

Ultrashort pulsed laser photoinscription of Ti:Sapphire crystals may result in the self-organization of nanoscale material redistribution regions in regular patterns within the laser trace and stress-induced birefringence around the laser trace. We report on the formation of anisotropic optical waveguides in Ti:Sapphire by a procedure that involves femtosecond laser inscription of adjacent nonguiding birefringent traces with nanopatterned crosssections and the accumulation of stress birefringence in the region between. Double parallel line structures with a separation of 25μm with vertical and horizontal nanoscale arrangements were written with a choice of orthogonal polarizations. Due to anisotropic light scattering on periodic nanostructures and stress-induced birefringence in the central zone, remarkable polarization dependent guiding effects were observed as a function of the microscopic geometry of the structures. Building on this polarization sensitivity, several structure such as 3 × 3 waveguide arrays, diamond and hexagon patterns are also investigated.

High-resolution bootstrapped differential semblance

We formulated two coherency measures, based on the bootstrapped differential semblance (BDS) estimator, that offered higher resolution in parameter tracking than did standard normalized differential semblance. Bootstrapping is a statistical resampling procedure used to infer estimates of standard errors and confidence intervals from data samples for which the statistical properties are unattainable via simple means, or when the probability density function is unkown or difficult to estimate. The first proposed estimator was based on a deterministic sorting of original offset traces by alternating near and far offsets to achieve maximized time shifts between adjacent traces. The near offsets were indexed with odd integers, while the even integers were used to index far offsets that were located at a constant index increment from the previous trace. The second was the product of several BDS terms, with the first term being the deterministic BDS defined above. The other terms were generated by random sorting of traces that alternated near and far offsets in an unpredictible manner. The proposed estimators could be applied in building velocity (and anellipticity) spectra for time-domain velocity analysis, depth-domain residual velocity update, or to any parameter-fitting algorithm involving discrete multichannel data. The gain in resolution provided by the suggested estimators over the differential semblance coefficient was illustrated on a number of synthetic and field data examples.

Impact of etch factor on characteristic impedance, crosstalk and board density

Signal integrity becomes more important when the length of the Printed Wiring Board (PWB) traces surpasses where λ denotes the wavelength. For fast digital communication purpose and low energy consumption in CMOS technology, faster rise time of the clock which means higher harmonic frequency, has always been preferable. In this case, the importance of considering signal integrity gets a higher priority as issues such reections and crosstalk between adjacent traces cannot be omitted, especially in dense High Density Interconnect (HDI) boards. Several factors control the effect of reections and the crosstalk such as the shape and dimension of the traces, the isolator characteristics which is inserted between the trace and the ground plane, the nearness and the geometry of the nearby conductors. In other words, these factors control the characteristic impedance of the traces and the mutual inductances and capacitances between the adjacent traces. Although these factors have been taken into account during the design phase for good signal integrity, the manufacturing process, which differs from vendor to vendor, has a great impact on the above factors. PWB manufacturing process may result in many different variations, which involve the dielectric constant, the thickness of the insulator, the trace width and the copper foil thickness. In addition to these variations, the etching quality that falls mainly in three different categories of trapezoidal trace form. In this paper we present the effect of three different etching shapes on the characteristic impedance. Moreover, it is concluded that one could gain space which can be used for shrinking the electronics and/or saving the raw material when trading the characteristic impedance error for space. Similar method is followed to investigate the crosstalk reduction between two adjacent microstriplines when tolerating the error in the characteristic impedance. This procedure can only be applied when a 90° etch angle process is feasible.

Cycloids for polishing along double-spiral toolpaths in configuration space

An automated polishing process of free-form surfaces requires a tool path that covers the entire surface equally and forms an overlapping pattern without visible artifacts. The recently presented double-spiral tool paths assure a coverage of the entire surface with a continuous, non-overlapping path and low variation in distance between adjacent traces of the path. We build upon this approach by constructing cycloids of flexible radii that fill the space between adjacent traces. The use of cycloids mimics the cyclic movement when polishing by hand. The approach operates in a precomputed configuration space (c-space) given in form of an adaptive quadrilateral heightfield mesh. Operating in c-space avoids having to deal with the issues of patch-boundary oscillations or long, stretched triangles in non-uniform rational b-spline surface or triangular mesh representations, respectively. Our algorithm computes appropriate spheroids that are intersected with the c-space to compute the cycloids. We derive a smooth representation of the cycloids using arcs in a rational Bezier formulation. We apply our approach to real-world examples to demonstrate its effectiveness in covering the entire surface with the desired polishing movements.

Recognition of Micro‐Seismic Events and Inversion in the Case of Single Seismic Phase

AbstractIn order to identify micro‐seismic events of single seismic phase and locate the identified microseismic events as well, we have researched the method of identifying the micro‐seismic events on the basis of the arrival time difference between any two traces in the case of single seismic phase and the characteristic rule of relationship of micro‐seismic events, spatial location of detector and the seismic phase velocity. First, by analyzing the internal variation of the arrival time difference and the above changes of variables, we establish the quantitative calculation relationship between the arrival time difference and every variable. Then, with regard to the arrival time differences of the adjacent trace and the first and the last trace of detector array, we research the specific expression of the quantitative calculation relationship. Given the spatial location of the event, we can calculate the distribution range of the above two kinds of arrival time differences using the relation expression above. Comparing the distribution range of two arrival time difference of the actual micro‐seismic events which we have calculated to the given event, we can identify the single seismic phase with the range which they fall to. Integrating the advances of the search method and the genetic algorithm, we put forward a micro‐seismic joint inversion method based on the solution domain constrained iterative forward model. From the analysis of the expectation probability distribution of the iterative error solution and the variations of different directions of the solutions, we establish the definition conditions of the domain of solution constraints. In the determinate scope of the solution domain, we carry out the inversion of micro‐seismic events using the genetic algorithm. Through the analysis of application of practical data, the method of identifying the micro‐seismic events reduces the error ratio of phase recognition greatly. According to the identified information, we do the inversion of actual data using the inversion method. Comparing with the actual situation, the result is consistent with the actual crack distribution, and is fairly good in convergence.

Interpolation with Fourier-radial adaptive thresholding

Many interpolation methods are effective with regularly sampled or randomly sampled data, whereas the spatial sampling of seismic reflectivity data is typically neither regular nor random. Fourier-radial adaptive thresholding (FRAT) is a sparsity-promoting method in which the interpolated result is sparse in the frequency-wavenumber domain and is coherent in a manner consistent with that of a collection of unaliased plane waves. The sparsity and the desired pattern in the [Formula: see text] domain are promoted by iterative soft thresholding and adaptive weighting; data in the [Formula: see text] domain are transformed to polar coordinates and then low-pass filtered along the radial axis to generate the nonlinear weight. FRAT interpolates data that are randomly sampled and aliased; i.e., where the minimum distance between adjacent traces is greater than the Nyquist sampling interval. A conventional approach to solving this problem is to apply a cascade of two procedures: first a sparsity-based method, such as projection onto convex sets (POCS) to interpolate the data onto a regularly sampled but aliased grid, followed by a “beyond aliasing” approach such as Gülünay [Formula: see text] interpolation to further interpolate the regularly sampled POCS result. In a simple synthetic example of two dipping plane waves with irregular, aliased sampling, FRAT outperformed this cascaded approach. In another experiment, the Sigsbee2A prestack synthetic data set was sampled using the source geometry from a 3D offshore survey where POCS will have difficulty with the semiregularity of this sampling pattern. FRAT produced results superior to those of POCS before and after the data were migrated.

Design of a Controllable Delay Line

Delay lines are used in printed circuit boards (PCBs) to produce delay between two points (or devices) while occupying as little board space as possible. As higher clock frequency is used in circuits, electromagnetic coupling between adjacent traces of delay line increases. The coupling that takes place between all the parallel adjoining traces combines synchronously or asynchronously to cause dispersion. Consequently, simple analytic techniques that predict delay line behavior are ineffective to predict precise delay and costly full-wave modeling or measurement becomes essential. In this paper, we consider microstrip meander delay lines and study the effect of the number of segments on resulting delay using full-wave modeling and measurement. We show that for short segments and when the number of segments is large enough, the resulting delay per segment is almost uniform and does not change as the number of segments increases. We show a linear relationship between the number of segments and the total delay, thus allowing for simple delay line design without the prohibitive cost of full-wave three-dimensional modeling of the entire delay line structure. Demonstration of these findings is supported by numerical simulations and experimental measurement.

Multichannel Seismic Deconvolution Using Markov–Bernoulli Random-Field Modeling

In this paper, we present an algorithm for multichannel blind deconvolution of seismic signals, which exploits lateral continuity of Earth layers based on Markov-Bernoulli random-field modeling. The reflectivity model accounts for layer discontinuities resulting from splitting, merging, starting, or terminating layers within the region of interest. We define a set of reflectivity states and legal transitions between the reflector configurations of adjacent traces and subsequently apply the Viterbi algorithm for finding the most likely sequences of reflectors that are connected across the traces by legal transitions. The improved performance of the proposed algorithm and its robustness to noise, compared with a competitive algorithm, are demonstrated using simulated and real seismic data examples, in blind and nonblind scenarios.

Calibration of Electromigration Reliability of Flip-Chip Packages by Electrothermal Coupling Analysis

Electromigration reliability of solder interconnects is dominated by current density and temperature inside the interconnects. For flip-chip packages, current densities around the regions where the traces connect a solder bump increase significantly due to the differences in feature sizes and electric resistivities between the solder bump and its adjacent traces. This current-crowding effect along with induced Joule heating accelerates electromigration failures. In this paper, the effects of current crowding and Joule heating in a flip-chip package are examined and quantified by three-dimensional electrothermal coupling analysis. We apply a volumetric averaging technique to cope with the current-crowding singularity. The volumetrically averaged current density and the maximum temperature in a solder bump are integrated into Black’s equation to calibrate the experimental electromigration fatigue lives.

An Integrated Signal and Power Integrity Analysis for Signal Traces Through the Parallel Planes Using Hybrid Finite-Element and Finite-Difference Time-Domain Techniques

This paper presents a numerical approach that combines the finite-element time-domain (FETD) method and the finite-difference time-domain (FDTD) method to model and analyze the two-dimensional electromagnetic problem concerned in the simultaneous switching noise (SSN) induced by adjacent signal traces through the coupled-via parallel-plate structures. Applying FETD for the region having the source excitation inside and FDTD for the remaining regions preserves the advantages of both FETD flexibility and FDTD efficiency. By further including the transmission-line simulation, the signal integrity and power integrity issues can be resolved at the same time. Furthermore, the numerical results demonstrate which kind of signal allocation between the planes can achieve the best noise cancellation. Finally, a comparison with the measurement data validates the proposed hybrid techniques.

Effects of Injection Systems and Plastic Mulches on Distribution and Emissions of Cis- and Trans-1,3-Dichloropropene and Chloropicrin

The concentration and distribution of a soil fumigant in the subsurface of field plots are two key factors in the determination of the fumigant efficacy. Subsurface concentrations of the biologically active compounds cis- and trans-1,3-dichloropropene (1,3-D) and chloropicrin (CP) were determined in soil at two adjacent injection traces and midpoint between the two traces in plastic-covered field beds after injection of the fumigant Telone C35 by conventional chisels or by a coulter rig (Avenger coulters). Two of the four beds were covered with metallic polyethylene film (MPE) and the remaining two were covered with virtually impermeable film (VIF). Three hours after chisel injection, concentrations of the three compounds at the two adjacent injection traces in the two beds were highly variable. Large concentrations of the compounds were detected at the side traces, whereas the compounds were not detected at the middle traces (bed centers) in the two chisel-injected beds covered with MPE or VIF. Initial concentrations of the three compounds at the two adjacent injection traces in the two Avenger-coulter-injected beds were more uniform than in the chisel-injected beds but still variable. Also, the three compounds had diffused horizontally to midpoint between the two injection traces in all four beds, generally in smaller concentrations. Concentrations of the three compounds in the shallow subsurface soil layer (0.5-30 cm) in the beds became progressively more uniform and then declined slowly. Volatilization losses from the two Avenger-coulter-injected beds and the chisel-injected bed covered with VIF were low. Combination of Avenger coulter injection and VIF provided better retention of the compounds in this soil layer and, thus, likely would provide better fumigant efficacy and crop yield.

Dynamic electrostatic force-gradient microscopy employing mechanoelectric cross modulation

This article describes a dynamic mode electrostatic force-gradient microscopy technique capable of high-frequency voltage measurement. The technique employs a wide-bandwidth implementation of a mechanoelectric cross-modulation scheme, where a microfabricated probe is driven by an amplitude-modulated sampling pulse and the sample is mechanically vibrated at a frequency different to that of electrical modulation. The resulting probe oscillation at the cross-modulation frequency provides local high-frequency voltage information. Unlike the force detection method, which is susceptible to poor resolution due to large coupling to the probe tip sidewall and cantilever, the force-gradient method provides an enhancement of spatial resolution. A significant reduction of interference from adjacent signal traces is demonstrated when performing integrated circuit testing. Quantitative high-frequency voltage measurement with high accuracy is achieved by using a null-force-gradient approach, but at the expense of reduced sensitivity.

Electrothermal coupling analysis of current crowding and Joule heating in flip-chip packages

Solder bumps serve as electrical paths as well as structural support in a flip-chip package assembly. Owing to the differences of feature sizes and electric resistivities between a solder bump and its adjacent traces, current densities around the regions where traces connect the solder bump increase in a significant amount. This current crowding effect along with the induced Joule heating would accelerate fatigue failure due to electromigration. In this paper we apply the three-dimensional electrothermal coupling analysis to investigate current crowding and Joule heating in a flip-chip package assembly carrying different constant electric currents under different ambient temperatures. Experiments are conducted to calibrate temperature-dependent electric resistivities of solder alloy, Al trace, and Cu trace, and to verify the numerical model by comparing calculated and measured maximum temperatures on the die surface. Through the electrothermal coupling analysis, effects of current crowding and Joule heating induced by different solder bump structures are examined and compared.

Higher-order-statistics and supertrace-based coherence-estimation algorithm

This article proposes a new higher-order-statistics-based coherence-estimation algorithm, which we denote as HOSC. Unlike the traditional crosscorrelation-based C1 coherence algorithm, which sequentially estimates correlation in the inline and crossline directions and uses their geometric mean as a coherence estimate at the analysis point, our method exploits three seismic traces simultaneously to calculate a 2D slice of their normalized fourth-order moment with one zero-lag correlation and then searches for the maximum correlation point on the 2D slice as the coherence estimate. To include more seismic traces in the coherence estimation, we introduce a supertrace technique that constructs a new data cube by rearranging several adjacent seismic traces into a single supertrace. Combining our supertrace technique with the C1 and HOSC algorithms, we obtain two efficient coherence-estimation algorithms, which we call ST-C1 and ST-HOSC. Application results on the real data set show that our algorithms are able to reveal more details about the structural and stratigraphic features than the traditional C1 algorithm, yet still preserve its computational efficiency.

Traces in Proximity to Gaps in Return Planes

Coupling between circuitry on printed circuit boards can be mitigated by a variety of well-known techniques. One such technique is to isolate circuitry in different areas of the printed circuit board by strategically placing a gap in the signal return plane. However, this technique is only effective at reducing common-impedance coupling, which is generally not a significant coupling mechanism at frequencies above 1 MHz. This paper investigates the effect of a gap located between and parallel to adjacent microstrip traces. The effect of the gap on the mutual inductance and mutual capacitance is evaluated. Laboratory measurements and numerical simulations show that gaps in the return plane are ineffective at reducing inductive and capacitive crosstalk in most configurations, and in some cases they increase the mutual coupling between printed circuit board traces.