Showing papers by "Jun Fan published in 2011"

Coaxial cable Bragg grating

Abstract: This paper reports a coaxial cable Bragg grating (CCBG) fabricated by drilling holes into the cable at periodic distances along the axial direction. Resonances were observed at discrete frequencies in both transmission and reflection spectra. The analogy of the CCBG with a fiber Bragg grating is shown. The grating was tested for the potential application as a strain-sensing device.

Equivalent Circuit Model for Power Bus Design in Multi-Layer PCBs With Via Arrays

Abstract: An equivalent circuit model for multilayer power planes with multiple via arrays is proposed. The complexity of the actual geometry is greatly reduced in the circuit model with the accuracy maintained. The model is corroborated by measurements.

Analytical expressions for transfer function of supply voltage fluctuation to jitter at a single-ended buffer

Abstract: In this paper, the transfer function of a supply voltage fluctuation to jitter is analytically solved for a single ended buffer in closed-form expressions. The expressions for the jitter transfer function is validated by comparison with HSPICE simulation, and applied to an example for statistical jitter estimation.

Inductance Calculations for Plane-Pair Area Fills With Vias in a Power Distribution Network Using a Cavity Model and Partial Inductances

Abstract: Partial inductances are computed herein for the via transitions between parallel planes. A hybrid method proposed for the inductance calculation correlates the definition of the partial inductance and a resonant cavity model. The hybrid method is corroborated by comparison with the partial-element equivalent-circuit and the cavity methods, as well as measurements. The portions of the plane net and via net inductances are quantified, and the contribution of each plane current to the plane net inductance is quantitatively analyzed.

An Extended Cavity Method to Analyze Slot Coupling Between Printed Circuit Board Cavities

Abstract: In high-speed multilayer printed circuit boards, gaps are commonly used in planes, where different areas are utilized for different logic levels or where noise isolation from one area to another is necessary. However, these gap structures could present serious signal integrity and electromagnetic interference issues. In this paper, an extended cavity method is developed to characterize noise coupling caused by slots or gaps in the middle plane of a three-plane structure. According to the equivalence principle, the entire structure can be divided into two plane pairs without any slot in the middle plane, and then, equivalent magnetic currents are needed in both plane pairs in the slot region to retain the same field distributions. Dyadic Green's functions of a rectangular cavity with perfect electric conductor top and bottom surfaces and perfect magnetic conductor sidewalls are derived for both electric and magnetic current excitations. Magnetic auxiliary ports with “magnetic voltage” and “magnetic current” are defined in the slot region to enable vertical connections of two plane pair. The conventional cavity model and segmentation technique are extended in this paper to handle such magnetic auxiliary ports. The proposed method can be used to effectively analyze the apertures with arbitrary shapes and is validated by full-wave simulations.

Measurement of multiple switching current components through a bulk decoupling capacitor using a lab-made low-cost current probe

Abstract: This paper presents a measurement-based data-processing approach to obtain parameters of multiple current components through a bulk decoupling capacitor for power integrity studies. A lab-made low-cost current probe is developed to measure the induced voltage due to the time-varying switching current. Then, a post data-processing procedure is introduced to separate and obtain the parameters of multiple current components. The results obtained by the proposed method are validated with other approaches.

Modeling and analysis of a trace referenced to a meshed ground plane

Abstract: Meshed planes are used in today's flexible PCB designs, and due to their non-homogeneous nature, Modeling of nearby interconnects increases in complexity. In this paper, a method to evaluate the effective characteristic impedance of a trace referenced to a meshed plane is proposed that is simpler and optimization based. The effective impedance and the per-unit-length parameters of the line were associated with the meshed plane periodical patterns as well as trace relative locations. A systematic study was performed to reveal the essential relationship between the meshed plane geometric parameters and the trace characteristics.

Analysis of via impedance variations with a Polynomial Chaos method

Abstract: In this paper, we propose a systematic framework for the optimization and analysis of the equivalent characteristic impedance of practical via structures. The framework consists of (a) optimizing via structures for impedance matching using a Genetic algorithm, and (b) numerically characterize, by Polynomial Chaos (PC) method, the sensitivity of the equivalent characteristic impedance to the manufacturing uncertainties in the various geometrical parameters of a via structure. The PC method can be effectively used to compute important statistical information, such as moments, probabilities and sensitivities with respect to the design variables. The PC method is straightforward to implement, and can be orders of magnitude faster than the traditional Monte Carlo (MC) method. The proposed framework naturally leads to a rigorous methodology for EM design/control in the presence of multiple sources of uncertainty.

Optimizing decoupling capacitor placement to reduce effective inductance

Abstract: Optimizing decoupling capacitor placement to insure rapid charge delivery is discussed in this paper. Placing additional decoupling capacitors in close proximity may reduce effective inductance but this inductance is only reduced under certain conditions.

Capacitance calculation for a shared-antipad via structure using an integral equation method based on partial capacitance

Abstract: An integral equation method used for capacitance extraction for axially symmetric geometries is extended in this paper to calculate the via-plane capacitances in shared-antipad via structures, by changing the circular ring cells to arc ones. The proposed method is validated with a commercial finite element method based tool for a typical structure used in modern high-speed printed circuit design.

On the possibility to detect and visualize electromagnetic coupling paths

Abstract: Out of the source - coupling path - victim concept, the coupling path is the most difficult to identify. This paper discusses several possible methods to detect and visualize electromagnetic coupling paths in EMC problems. The authors do not have a ready-made solution and hope this paper could inspire others to join us in the search of methods for the detection and visualization of coupling paths.

Estimation of crosstalk among multiple stripline traces crossing a split by compressed sensing

Abstract: In printed circuit board (PCB) designs, it is common to split power/ground planes into different partitions, which leads to more crosstalk among signal traces that route crossing a split. It is of general interest to develop a crosstalk model for various geometric parameters. However, the long time required to simulate the structure with any given set of geometric parameters renders general modelling approaches such as interpolation inefficient. In this paper, we develop an empirical model based upon the compressed sensing technique to characterize the crosstalk among traces as a function of geometric parameters. A good agreement between the empirical model and full-wave simulations is observed for various test examples, with an exceptionally small number of samples.

Parametric study on the effect of asymmetry in multi-channel differential signaling

Abstract: The effects of geometric asymmetry on the electrical performance of multi-channel differential signaling in printed circuit boards are investigated in this paper. The asymmetry, which is the origin of noise coupled through mode conversion, is difficult to control in real channel structures, where a large number of vias and traces are populated. Supported by an efficient parametric simulation tool, this paper presents the effects of the asymmetry on mode conversion and differential mode crosstalk in real multi-channel structures. This extensive parametric study was used to define design guidelines to suppress this noise coupling by adding ground vias in strategic locations.

Coaxial Cable Bragg Grating Sensors for Large Strain Measurement

Abstract: In this paper, a new coaxial cable Bragg grating (CCBG) is developed as a strain sensor and the sensor's capacity for large range strain measurement in structural health monitoring (SHM) is demonstrated for the first time. The sensor device is comprised of regularly spaced periodic discontinuities along a coaxial cable. The discontinuities are fabricated using a computer numerical controlled (CNC) machine to drill holes in the cable. Each discontinuity generates a weak reflection to the electromagnetic wave propagating inside the cable. Superposition of these weak reflections produces a strong reflection at discrete frequencies that can be explained by Bragg grating theory. By monitoring the resonant frequency shift of the sensor's reflection or transmission spectra, strain measurement sensitivity of 20μe and a dynamic range of 50000μe (5%) were demonstrated for axial strain measurements. The experimental results show that the CCBG sensors perform well for large strain measurement needed in structural health monitoring (SHM).

Compressed sensing based analytical modeling for Through-Silicon-Via pairs

Abstract: Through-Silicon-Vias (TSVs) are the critical enabling technique for three-dimensional integrated circuits (3D ICs). While there are a few existing works in literature to model the electrical performance of TSVs, they are either for fixed geometry or in lack of accuracy. In this paper, we use compressed sensing technique to model the electrical performance of TSV pairs. Experimental results indicate that with an exceptionally small number of samples, our model has a maximum relative error of 3.94% compared with full-wave simulations over a wide range of geometry parameters and frequencies.

Near-field H to E transformation using plane wave spectrum theory

Abstract: Near-field measurements are widely used to indicate the radiation from integrated circuits (IC). To minimize the number of field components measured in a near-field scan, it is necessary to calculate the electric field from magnetic field or vice versa. In this paper, a method based on plane wave spectrum theory is proposed to perform the H to E transformation, and a filtering technique is proposed to address the noise problem in the calculation. A simple active circuit in a 3-D full-wave simulation tool is used to validate this method. This method is useful to reduce the number of field components to be measured, resulting in faster near-field scanning.

Statistical estimation of root mean square crosstalk in SFP+ cable evaluations

Abstract: A rigorous statistical estimation of the root mean square equation is proposed for near-end crosstalk simulation in SFP+ cable evaluations. This method employs the pulse response, the near-end output in the victim pair due to a single-pulse input of one bit long in the aggressor pair. This pulse response can be obtained from vector network analyzer (VNA) measurements. Thus SFP+ cable evaluations can be effectively performed using easier and more accurate frequency-domain measurements, instead of the time-domain ones defined in the specification.