Showing papers by "Jun Fan published in 2013"

An Improved Dipole-Moment Model Based on Near-Field Scanning for Characterizing Near-Field Coupling and Far-Field Radiation From an IC

Abstract: In this paper, an improved dipole-moment model for characterizing near-field coupling and far-field radiation from an IC based on near-field scanning is proposed. An array of electric and magnetic dipole moments is used to reproduce the field distributions in a scanning plane above an IC. These dipole moments can then be used as noise sources for the IC. In order to ensure the accurate prediction of the near-field coupling from the IC, the regularization technique and the truncated singular-value decomposition method are investigated in this paper, together with the conventional least-squares method, to reconstruct the dipole moments from the near-field scanning data. A simple example is used to demonstrate the approach. The improved dipole-moment model is particularly useful for addressing radio-frequency interference issues where near-field noise coupling needs to be accurately analyzed.

An Effective Method of Probe Calibration in Phase-Resolved Near-Field Scanning for EMI Application

Abstract: Near-field scanning can be used to determine the far-field emissions of electronic devices. In general, this requires phase-resolved electric and magnetic near-field data. To capture a broad frequency range relatively quickly, a multichannel oscilloscope can be used for data capture. The phase relationship of the fields between different space points and between the electric and the magnetic field needs to be known. Consequently, it is required to determine the complex-valued probe factor (PF) of the probe, cable, and amplifier chain. This paper presents a fast and efficient calibration method which uses the same setup and instruments during calibration and measurement, and it allows for easy and economical integration of the calibration hardware and software into the scanning system. Known fields are created by a microstrip trace driven with a comb generator. By referencing measured data to this known field, the PF is obtained over a broad frequency range by capturing one time-domain waveform.

Estimating Radio-Frequency Interference to an Antenna Due to Near-Field Coupling Using Decomposition Method Based on Reciprocity

Abstract: In mixed radio-frequency (RF) and digital designs, noise from high-speed digital circuits can interfere with RF receivers, resulting in RF interference issues such as receiver desensitization. In this paper, an effective methodology is proposed to estimate the RF interference received by an antenna due to near-field coupling, which is one of the common noise-coupling mechanisms, using decomposition method based on reciprocity. In other words, the noise-coupling problem is divided into two steps. In the first step, the coupling from the noise source to a Huygens surface that encloses the antenna is studied, with the actual antenna structure removed, and the induced tangential electromagnetic fields due to the noise source on this surface are obtained. In the second step, the antenna itself with the same Huygens surface is studied. The antenna is treated as a transmitting one and the induced tangential electromagnetic fields on the surface are obtained. Then, the reciprocity theory is used and the noise power coupled to the antenna port in the original problem is estimated based on the results obtained in the two steps. The proposed methodology is validated through comparisons with full-wave simulations. It fits well with engineering practice, and is particularly suitable for prelayout wireless system design and planning.

A Coaxial Cable Fabry-Perot Interferometer for Sensing Applications

Abstract: This paper reports a novel coaxial cable Fabry-Perot interferometer for sensing applications. The sensor is fabricated by drilling two holes half-way into a coaxial cable. The device physics was described. The temperature and strain responses of the sensor were tested. The measurement error was calculated and analyzed.

A Magnetic-Field Resonant Probe With Enhanced Sensitivity for RF Interference Applications

Abstract: High-sensitive field probes are highly desirable for radio-frequency (RF) interference studies, where ultralow noise levels are of interest. By incorporating an LC resonant circuit in a differential-loop probe, together with a Marchand balun, a magnetic-field probe with enhanced sensitivity is developed. Its equivalent circuit model and design methodology are established. The design is validated by measurements. The measured relative sensitivity in terms of |S21| of the proposed probe increases by approximately 8.63 dB at the resonant frequency of 1.575 GHz compared to that of a conventional design. The advantage of the proposed probe is validated through its application in the measurement of a microstrip trace and a real-world cell phone design.

Analytical Transfer Functions Relating Power and Ground Voltage Fluctuations to Jitter at a Single-Ended Full-Swing Buffer

Abstract: The transfer functions relating supply voltage fluctuations to jitter are analytically derived in closed form expressions for a single-ended buffer. The analytic transfer functions are derived from a linear differential equation obtained from asymptotic linear inverter I-V curves. The transfer functions are validated by comparison with HSPICE simulations. The estimated jitter is compared with the simulated jitter using eye diagrams with single-frequency and multitone supply voltage fluctuations.

Modeling and Application of Multi-Port TSV Networks in 3-D IC

Abstract: Through-silicon-via (TSV) enables vertical connectivity between stacked chips or interposer and is a key technology for 3-D integrated circuits (ICs) While arrays of TSVs are needed in 3-D IC, there only exists a frequency-dependent resistance, inductance, conductance and capacitance circuit model for a pair of TSVs with coupling between them In this paper, we develop a simple yet accurate circuit model for a multiport TSV network (eg, coupled TSV array) by decomposing the network into a number of TSV pairs and then applying circuit models for each of them We call the new model a pair-based model for the multiport TSV network It is first verified against a commercial electromagnetic solver for up to 20 GHz and subsequently employed for a variety of examples for signal and power integrity analysis

Improved Target Impedance for Power Distribution Network Design With Power Traces Based on Rigorous Transient Analysis in a Handheld Device

Abstract: The concept of target impedance can be significantly improved, based on the rigorous closed-form expressions for transient supply voltage ripple excited by an integrated circuit (IC) switching current, for the power distribution network (PDN) with power traces that is commonly used in handheld devices. A systematic procedure for developing the target impedance is formulated, which is then applied to the PDN design of a handheld product. From measurements of transient IC switching currents, PDN impedance, and supply voltage ripple, it is shown that the proposed target impedance successfully correlates the PDN impedance in the frequency domain with the transient supply voltage ripple in the time domain.

Optimization of the transition from connector to PCB board

Abstract: A transition from vertically launched coaxial connector to routed trace on board is simulated and optimized to achieve very small reflections for precise TRL calibration. The mismatch of the discontinuities in the transition was reduced by controlling the via-impedance, introducing capacitive via-pads and applying diving boards. Each segment was optimized first, and then the whole cascaded structure was simulated to achieve the optimized smooth signal transition.

Measurement validation of the dipole-moment model for IC radiated emissions

Abstract: A procedure is proposed to extract equivalent dipole-moment model for the real integrated circuit (IC) from the near-field scanning data. The radiation fields from the extracted dipole-moment model match well with the measured ones in both near- and far-fields. Therefore, the dipole-moment model can be applied to take the place of real IC in the full-wave simulation tools, to predict the IC's radiated emissions with the presence of other structures. Radiation from a heat sink excited by the dipole-moment model of an IC has been simulated by HFSS. The simulated results were found to agree with those measured. Thus, the extraction procedure of dipole-moment models for IC radiation emission has been validated.

Heat-Sink Modeling and Design With Dipole Moments Representing IC Excitation

Abstract: Electromagnetic field coupling and radiation from a heat sink is a challenging issue in the electromagnetic compatibility design of high-speed circuits. In order to accurately predict the fields excited by a heat sink, an approach is proposed in this paper to include the equivalent excitation of the heat sink, which is described by some dipole moments constructed from the near-field scanning of the integrated circuit beneath the heat sink. With both the dipole moments and the passive heat-sink structure incorporated in a full-wave model, near-field coupling and far-field radiation can be estimated, and the heat-sink structure can be optimized for mitigating unintentional interferences. Two examples are used to validate and demonstrate the proposed approach.

Modeling Local Via Structures Using Innovative PEEC Formulation Based on Cavity Green's Functions With Wave Port Excitation

Abstract: Complex via structures such as noncircular antipads are rigorously studied, in the local region close to vias, using an innovative partial-element equivalent-circuit (PEEC) formulation based on the cavity Green's functions. The problem under study is an essential building block that can be used to model complex multilayer structures. With the usage of the cavity Green's functions, the number of unknowns is significantly reduced. Further, nonorthogonal quadrilateral mesh is used to better accommodate the complex shape of the antipads in practical designs. A novel wave port excitation method is proposed, which is new for the PEEC formulations. Singularity extraction in self element calculations involving the nonorthogonal cell and the cavity Green's functions is studied. The impedance parameters of several via structures are obtained using the proposed method, and the results are validated with the finite-element solution from a commercial tool.

Investigation of interference in a mobile phone from a DC-to-DC converter

Abstract: Turning on the LCD screen of a mobile phone causes desensitization of its receiver in the GSM lower frequency band (900 MHz). In this paper, the measurement techniques used for the investigation of intra-system interference in a mobile phone caused due to the DC-DC converters present on-chip the LCD driver IC are presented. An equivalent noise source model is created by modelling the flexible printed circuit board traces and obtaining a Thevenin equivalent noise by changing the load conditions.

An EMD-SVR method for non-stationary time series prediction

Abstract: In the area of prognostics and health management, data-driven methods increasingly show the superiority against model-based method due to the complex relationships and learn trends available in the data captured without the need for specific failure models. This paper uses Empirical Mode Decomposition (EMD) and Support Vector Machine (SVM) to build a model for non-stationary time series prediction. And it proves that the EMD-SVR method can solve the problem of few training samples in modeling the path of performance degradation. Then when the threshold is given, we can forecast the lifetime of engineering systems based on the performance degradation data.

QoI-Aware Energy-Efficient Participatory Crowdsourcing

Abstract: Today's smartphones not only serve as a means of personal communication device, but are also fundamentally transforming the traditional understanding of crowdsourcing to an emerging type of participatory, task-oriented applications. It aims to support the so-called Citizen Science efforts for knowledge discovery, to understand the human behavior and measure/evaluate their opinions. In this paper, to facilitate the above scenarios, we propose a novel energy-efficient participatory crowdsourcing framework that meets the quality-of-information (QoI) requirements of the request in a distributed manner. Specifically, we extend the traditional framework of Gur Game for distributed decision-making to recommend the level of information contribution for each participant, by merging the multiple automaton chains into a single chain with multiple steady states. We evaluate the proposed scheme under the MIT social evolution data set, where the QoI requirements of the request are successfully achieved, with a satisfactory level of energy consumption fairness among participants, of negligible computational complexity. Finally, we explore the impact of community structure on the proposed algorithm, and propose a feasible method to facilitate the local data aggregation.

ASIC package to board BGA discontinuity characterization in >10Gbps SerDes links

Abstract: High performance ASIC packages are typically mounted on the PCB using BGA solder ball technology; ASIC package to board BGA transition creates impedance discontinuity in the multi-gigabit signaling channel. It is important to understand and model this discontinuity accurately to improve end to end channel design in system level. Usually when the channel is simulated, instead of modeling the package with the PCB together in one model, also known as one piece model, separate models are built for package and PCB and the individual models are then cascaded using the circuit simulator. If the models are not setup correctly in the field solvers, i.e. port definition, it may not capture the transition behavior correctly and hence makes the cascaded channel model results differ from one piece model and/or real channel measurement. This paper discusses the detailed modeling of the BGA solder ball transition to enable the model concatenation method suitable to be used for system level channel prediction. The package only model, board only model and one piece model were simulated upto 20GHz using either lump port or wave port setup in ANSYS HFSS field solver. The cascaded model with wave port connection and one piece model are found well matched. The lump-port connection can introduce extra parasitic inductance at the BGA connection point and hence is not recommended. Hardware (package and PCB test samples) have been built to characterize this transition behavior for model to hardware correlation. The FSA (Feature Selected Validation) method is used to quantify the correlation results, both insertion loss and return loss are compared to gain confidence on the simulation results and high-speed channel prediction.

Modeling of Crosstalk Between Two Nonparallel Striplines on Adjacent Layers

Abstract: Crosstalk between two nonparallel striplines on adjacent layers is investigated. An equivalent per unit length model for nonparallel lines is developed based on multiconductor transmission line theories and the Nelder-Mead optimization algorithm. The physical meaning of the equivalent model is explained for different test geometries. Empirical formulas, as functions of various geometric parameters, are derived based on multivariable curve fitting for a set of defined trace geometries. The validity of the empirical model is confirmed through comparison with different test examples.

Capacitance Calculation for Via Structures Using an Integral Equation Method Based on Partial Capacitance

Abstract: In this paper, a new integral equation formulation for via structures is developed for the capacitance extraction between vias and planes. The formulation is initially developed for axially symmetric geometries and then extended to axially asymmetric geometries by changing the circular ring cells to arc cells. The extended method can be used to calculate the shared-antipad via structure, which is widely used in high-speed differential signal interconnects. In addition, the image theory is used to handle inhomogeneous media, and a new technique is given to reduce computational costs for via-to-plane structures based on properties of the capacitance-matrix elements. The proposed method is validated with a commercial finite element method-based tool for several practical via structures. The extracted capacitance is also incorporated into the physics-based via model and validated with full-wave simulations.

De-embedding techniques for transmission lines: An exploration, review, and proposal

Abstract: In this paper, two transmission line based de-embedding techniques are reviewed for application in 3D IC measurements. In particular, full-wave models of extremely small stripline geometries are investigated. The advantages and drawbacks of each method are discussed in reference to simulation results, and a new hybrid method is proposed.

Investigating intra-system radio-frequency interference from high-speed traces to a GPS patch antenna

Abstract: High-speed traces routed in close proximity to a GPS patch antenna in a compact consumer electronic device could cause desensitization of the GPS receiver. Noise coupling mechanisms between the traces and the antenna are studied, together with the field patterns of the patch antenna. The insights gained in the understanding of the underlying coupling physics are further used to develop general trace routing rules for minimizing radio frequency interference in the GPS band.

Efficient complex broadside coupled trace modeling and estimation of crosstalk impact using statistical BER analysis for high volume, high performance printed circuit board designs

Abstract: Increase in the cost of printed circuit board (PCB) with the increase in layer count has led to the design of PCB stack-ups that have broadside coupled signals. Broadside coupling of signals in adjacent layers also leads to crosstalk that can be sometimes difficult to model and quantify in terms of its impact on receiver eye opening. The difficulty stems from the fact that in most boards, broadside coupling occurs between the signal traces at various angles and at multiple instances. The challenges involved in modeling include generating models for the broadside coupled section quickly without the overhead of time consuming full-wave simulations. Full wave simulations are time and memory intensive especially for coupled traces at an angle and real board designs can have hundreds of them. The simulation challenges include predicting the impact of crosstalk on bit error rate (BER) accurately. In this paper, the focus is on alleviating the modeling challenges by using fast equivalent per unit length (Eq. PUL) [1, 10] resistance, inductance, conductance, capacitance (RLGC) method for the broadside coupled traces crossing at an angle and to resolve the simulation challenge by seamlessly integrating the models into statistical simulation approach that can quantify the eye opening at various BERs that would help electrical designers to come up with set of design and routing guidelines that can save PCB cost and at the same time maintain electrical integrity.

Study of cross polarization of tapered slot antenna for EMC measurements

Abstract: Development of wireless technologies pushes for more accurate and more consistent EMC measurements. Antenna cross polarization is found to be a main contributor to the measurement errors. In this paper, full-wave analysis of E-field distribution of various slotlines is presented, which reveals that the bilateral tapered slot antenna has the widest impedance bandwidth and the lowest cross-polarization level simultaneously. The conclusions obtained in this paper will be used to develop an innovative wideband (from 700 MHz to 20 GHz) bilateral tapered slot antenna used for wireless EMC testing.

Towards Energy-Efficiency in Selfish, Cooperative Networks

Abstract: Cooperative communication has been proven effective in enhancing the performance of wireless networks, anda variety of techniques have been investigated to exploit the spatial diversity gain to provide reliable physical layer communications with multiple quality-of-service (QoS) requirements. In this paper, we propose an adaptive multi-relay selection with power allocation mechanism to offer energy fairness at each node for a cooperative network. Unlike traditional approaches where all nodes are considered to transmit in a collaborative manner, weexplicitly consider the situation where nodes exhibit some degree of selfish behavior. Specifically, we introduce anovel concept of the selfishness index and incorporate it into a utility function which denotes the degree a node can benefit from cooperative transmission. Theoretical analysis and extensive simulation results are supplemented toshow advantages in maximizing the network lifetime and guaranteeing the QoS in realistic wireless environments. We also consider the practical situation when nodes consume energy in mode switching, and carefully study the behavior of inter-cluster relay switching and the trade-off among network lifetime, switching cost and switching frequency.

The application of spark gaps on audio jack for ESD protection

Abstract: ESD strikes can be suppressed by placing ESD protection devices along ESD current paths. As primary ESD protection on PCBs, spark gaps are cheap and take little space, but the breakdown voltage is not low enough and the lag time can be too long to protect the circuit. The effect of adding carbon and non linear polymers to the spark gap is investigated in this paper.

Fair and energy-efficient cooperative relaying with selfish nodes

Abstract: Cooperative communication has been proven effective in enhancing the performance of wireless networks. In this paper, we propose an adaptive multi-relay selection with power allocation mechanism to offer energy fairness at each node for a cooperative network. Unlike traditional approaches where all nodes are considered to transmit in a collaborative manner, we explicitly consider the situation where each node exhibits some degree of selfishness behavior. By introducing novel concepts of the selfishness index and utility function which denote node's benefit from cooperation, we show that the proposed cooperation scheme can well balance the energy consumption among nodes as well as maximize the network lifetime. Theoretical analysis and extensive simulation results are supplemented to show advantages of the proposed approach in power saving and power allocation fairness.