Showing papers by "Jun Fan published in 2016"

A Simple Miniature Ultrawideband Magnetic Field Probe Design for Magnetic Near-Field Measurements

Abstract: A simple miniature magnetic-field probe for near-field measurements in 9-kHz–20-GHz bandwidth, which is applied to high-speed circuits, has been proposed and manufactured. The magnetic-field probe is built on a four-layer printed circuit board (PCB) using high-performance and low-loss Rogers material ( $\varepsilon _{r}= 3.48$ and tan $\delta = 0.0037$ ). Electric field coupling can be suppressed by PCB shielding structure of the magnetic-field probe. Coax-thru-hole via array technique is used to achieve impedance match. The resonance in working frequency band is suppressed through via fence, making $\vert S_{21}\vert $ rather smooth in the operation band. Experimental results show that the working frequency band is up to 9 kHz–20 GHz.

Radio-Frequency Interference Estimation Using Equivalent Dipole-Moment Models and Decomposition Method Based on Reciprocity

Abstract: In modern electronic products, the noise from high-speed digital parts is likely to interfere with nearby receivers, causing radio-frequency interference (RFI) issues. In this paper, the equivalent dipole-moment models and a decomposition method based on reciprocity theory are proposed being used together to estimate the coupling from the noise source to the victim antennas. The dipole-moment models are extracted from the near fields of the noise source by solving the inverse problem. The tangential electromagnetic fields on a Huygens's surface, which enclose the victim antenna, can be calculated from these equivalent dipole-moment models. Then, the victim antenna only is treated as a radiator. The tangential electromagnetic fields from the radiating antenna on the same Huygens's surface can be obtained. With these two groups of the fields on the Huygens's surface, the reciprocity theory is applied to estimate the coupling from the noise source to the victim antenna. This method is validated by full-wave simulations and measurements of a simple printed circuit board. The proposed method provides convenience to estimate RFI issues in the early design stage and saves the time of RFI simulation and measurements.

Formulation and Network Model Reduction for Analysis of the Power Distribution Network in a Production-Level Multilayered Printed Circuit Board

Abstract: A methodology for modeling the power delivery network from the voltage regulator module to the pins of a high pin count integrated circuit on a printed circuit board (PCB) is presented. The proposed model is based on inductance extraction from first principle formulation of a cavity formed by parallel metal planes. Circuit reduction is used to practically realize the model for a production level, complex, multilayer PCBs. The lumped element model is compatible with SPICE-type simulators. The resulting model has a relatively simple circuit topology. The model is corroborated with microprobing measurements up to a few gigahertz. The model can be used for a wide range of geometry variations in a power integrity analysis, including complex power/ground stack up, various numbers of decoupling capacitors with arbitrary locations, numerous IC power pins and IC power/ground return via layouts, as well as hundreds of ground return vias.

Fast and Accurate TIS Testing Method for Wireless User Equipment With RSS Reporting

Abstract: A fast and accurate total isotropic sensitivity (TIS) testing method for wireless user equipment based on radiated sensitivity measurement and received signal strength (RSS) reporting is proposed in this paper. Innovative techniques for avoiding the effects of RSS reporting errors on TIS accuracy and reducing the total TIS measurement time are presented and incorporated into the testing procedures. The proposed method is suitable for receiver sensitivity testing of single input, single output radio systems having RSS reporting such as cellular communication, WiFi, and Bluetooth systems.

Analytical and numerical sensitivity analyses of fixtures de-embedding

Abstract: De-embedding procedures are sensitive to manufacturing variations in test fixtures, as well as inaccuracies associated with the calibration and measurement process. Such sensitivities can propagate through de-embedding procedures, resulting in amplified errors. In this paper, analytical and numerical techniques are used to perform sensitivity studies on both simulation and measurement data, with respect to de-embedding.

Interferogram Reconstruction of Cascaded Coaxial Cable Fabry-Perot Interferometers for Distributed Sensing Application

Abstract: This paper describes a distributed sensing concept using coaxial cable-based Fabry-Perot interferometers (CCFPIs). Multiple reflectors are implemented along a coaxial cable, where every two consecutive reflectors can be considered as a low finesse CCFPI, which has a relatively weak reflection coefficient and insertion loss. The interferogram in a frequency domain of each individual CCFPI could be reconstructed through the proposed signal processing method, so that the phase detection could be applied to any CCFPIs on one cable to achieve high measurement accuracy. A large capacity sensor network with a relatively high measurement accuracy can be implemented simultaneously. The concept takes advantage of the time-domain multiplexing method and the pure frequency domain measurement, which is herein called a joint-time-frequency demodulation technique. Due to its effectiveness and robustness, the device is especially attractive for structural, downhole, or underwater applications.

Plane-Pair PEEC Model for Power Distribution Networks With Sub-Meshing Techniques

Abstract: We present an improved plane-pair partial element equivalent circuit (PEEC) model for power distribution network modeling based on the PEEC formulation. The model can include via connections, decoupling capacitor macro-models, and discontinuities such as holes in the plane-pairs. An efficient approximate inductance sub-meshing model is described for large printed circuit plane-pairs with complex geometries and numerous vias. The modified nodal analysis (MNA) used leads to a flexible circuit solution where we can compute inductances, resistances, impedances, or other circuit models, including dc solutions. The MNA equations include effective optimizations such as the placement of capacitors. Today, a large class of methods are available based on numerous formulations including finite-difference time-domain, finite-element method, integral equation model, and cavity models. Each of the approaches has its own type of problems for which it is most suitable.

Radiation Noise Source Modeling and Application in Near-Field Coupling Estimation

Abstract: Near-field coupling in mixed digital/RF circuit design is critical to system sensitivity for modern high speed electronic systems. This paper presents radiation noise source modeling methods and applies equivalent noise source models to near-field coupling estimations. The noise source can be either modeled by physics-based dipole moment model or Huygens's equivalent model with data obtained from near-field scanning. The fundamental principles of both methods are first studied by simulation. A clock buffer integrated circuit is first modeled as a dipole moment model. The tangential fields on Huygens's box can be calculated by a dipole moment model with negligible multiple scattering effect assumption. The noise coupling then can be obtained by surface integration of Poynting vector at the RF antenna receiving port by full-wave simulation.

Validating the transmission-line based material property extraction procedure including surface roughness for multilayer PCBs using simulations

Abstract: Accurate frequency-dependent dielectric properties are important for accurate modeling of signal and power integrity problems. One method for extracting dielectric properties from fabricated multilayer printed circuit boards is based on the measured electrical property of fabricated transmission lines, denoted the “Root-omega” method. In this paper, the “Root-omega” method applied to the cases with smooth and rough conductors is validated using simulations. Potential errors in the procedure are discussed.

Estimating the near field coupling from SMPS circuits to a nearby antenna using dipole moments

Abstract: In this paper, the near field coupling from SMPS circuits to a nearby antenna is studied using dipole moments [1]. The dipole moments are extracted from scanned H fields on a plane above SMPS circuits, and then imported into an HFSS model to do full wave simulation. The simulated coupling matches well with direct measurement. Methods to resolve magnitude and phase of near fields of SMPS noise source are introduced. Error analysis is included in the end as well.

Fast Method for OTA Performance Testing of Transmit–Receive Cofrequency Mobile Terminal

Abstract: This paper provides a novel method for measuring of a wireless user equipment, when the equipment uses the same frequency for both transmitting and receiving. The proposed method is based on the fact that the total radiated power (TRP) and the total isotropic sensitivity patterns are complementary for transmit–receive cofrequency mobile terminals. Thus, the proposed method only requires a full TRP test and an accurate efficient isotropic sensitivity test to complete a total OTA performance measurement, resulting in improved test accuracy and decreased measurement time compared to the traditional test method defined in the OTA testing standard. The proposed method is suitable for OTA testing of transmit–receive cofrequency and single-input single-output radio systems, such as cellular communication, Wi-Fi, ZigBee, and Bluetooth.

Extracting characteristic impedance of a transmission line referenced to a meshed ground plane

Abstract: Meshed power and ground planes are commonly used in today's flexible printed circuit board (PCB). In this paper, a methodology to extract the effective characteristic impedance as well as the per-unit-length parameters of a transmission line with a meshed reference plane is proposed based on an equivalent transmission line model. The validity of this methodology is confirmed through comparison with full-wave simulations.

PAM4 signaling considerations for high-speed serial links

Abstract: The paper discusses current challenges and advantages of multi-level signaling for high-speed serial links, showing the differences and similarities in link-path analysis between binary and multi-level signaling. Comparison of two signaling methodologies is given from the general theory viewpoint, as well as on the basis of various tests regarding crosstalk, jitter, equalizations and different channel characteristics, such as material, impedance and overall manufacturing design sensitivity.

Radio-frequency interference estimation by reciprocity theorem with noise source characterized by Huygens's equivalent model

Abstract: Noise coupling from a working IC to the neighboring victim antenna is estimated by decomposition based reciprocity theorem. The overall problem is decomposed into two parts. In the first part, the IC is turned on and the victim antenna is turned off, which is defined as forward problem. The second part is called reverse problem in which case the victim antenna is excited while the IC is turned off. An imaginary Huygens's box is introduced above the victim antenna for evaluating the coupled power from noise source to the victim RF antenna. The noise source is characterized by Huygens's equivalent source in the forward problem, and the victim antenna is modeled in full-wave simulation tool. With tangential E and H fields obtained in both forward problem and reverse problem, the coupled power can be estimated by numerical calculation of reciprocity theorem. The method by using Huygens's equivalent source is first validated by simulation in the forward problem. Later a test board with an IC and patch antenna is further measured to validate the overall methodology.

Noise coupling path analysis for RF interference caused by LCD noise modulation

Abstract: RF interference caused by liquid crystal display (LCD) noise modulation in a mobile phone was investigated and its noise coupling path was demonstrated. In the frequency division duplex communications, mobile phones can send (uplink) and receive (downlink) at the same time. When an antenna transmits high power signal, the baseband noise from an LCD panel is modulated into an RF band and causes interference in a receiving antenna. A noise coupling path between an antenna and a display driver IC, which drives the LCD panel, was experimentally demonstrate. In addition, a simple noise source model was proposed to represent modulation mechanism. A network analysis with the modulation model showed good correlation with the measured spectra of the modulated noise in a receiving antenna.

Variability analysis of crosstalk among pairs of differential vias using polynomial-chaos and design of experiments methods

Abstract: The variability of the worst-case crosstalk among differential vias in response to the change of the relative locations of the ground and the differential vias are studied in this work. The polynomial-chaos (PC) and the design of experiments (DoE) methods are applied to construct the statistical models. Both methods work well. But the DoE method is preferred in our case since it takes fewer simulations.

Capacitance-Enhanced Through-Silicon Via for Power Distribution Networks in 3D ICs

Abstract: The through-silicon via (TSV) structure with enhanced capacitance is proposed for the power distribution network in 3D ICs, where an n+ contact on the top surface surrounding the oxide-silicon interface of the power TSV is used, instead of a p-substrate. The n+ contact supplies the majority carrier to the channel, so the inversion layer can be formed at high frequencies. Since power TSVs are always biased to a voltage higher than the threshold voltage, changing the depletion layer to an inversion layer enables the larger capacitance in the proposed TSV. The voltage and frequency characteristics of the proposed TSV structure are simulated and compared with the conventional structure. In addition, a model based on $RC$ transmission line is proposed to estimate the capacitance degeneration at high frequencies. The model showed a good match with simulated results over a wide frequency range.

Simulation challenges in system level electrostatic discharge modeling

Abstract: Simulation of system level electrostatic discharge (ESD) is challenging due to the complexity of electronic systems, missing soft failure models for ICs and the modeling of arcing. This paper details these difficulties and points at examples of successful solutions for modeling ESD generators in SPICE and full wave, modeling of arc behavior, and simulation of ESD into products causing soft-failures.

Analytical equivalent circuit modeling for multiple core vias in a high-speed package

Abstract: Core vias found in the packages of high-speed ICs can have a large impact on overall channel performance. Thus accurately modeling core vias in the package is essential. In this paper analytical methodologies are used to calculate equivalent circuit models of core vias.

Fast Band-Sweep Total Isotropic Sensitivity Measurement

Abstract: To provide consistent measurements of radio performance in typical complex environments, the total isotropic sensitivity (TIS) is used as a key parameter measured in anechoic chambers. Currently, the TIS measurement is based on the integration of the measured effective isotropic sensitivity at every angle over a spherical surface. This measurement is time consuming so it is only performed for three channels in a band in order to reduce overall measurement time. However, the whole band performance in real environments is critical in the research and development stage, and even in potential certification measurement. A novel fast band-sweep measurement for TIS of wireless devices is proposed in this paper. This method measures the radiated sensitivity and the average gain of the receiver antenna separately, and then combines them to obtain the TIS. The measurement of the radiated sensitivity in a band is efficiently performed based on the relationship between the bit error rate and the received power, and the band-sweep average gain of mobile antennas can be achieved through peak gain measurements. Hence, this method reduces band-sweep measurement time significantly and also ensues the measurement accuracy by eliminating the systematic error in the received signal strength indicator reporting.

Radiation Physics and Design Guidelines of High-Speed Connectors

Abstract: High-speed connectors contribute to system-level electromagnetic interference (EMI). Radiation from antenna-mode current and transmission-line (TL)-mode current is briefly reviewed with a backplane connector and an optical cage connector. The radiation from the high-speed connector with TL-mode current is analyzed in detail. The possible radiation mechanisms are analyzed respectively through Green's function method, steepest descent method, and electromagnetic compatibility studio method of moment. Design guidelines of high-speed connectors for EMI mitigation are proposed based on the analysis of radiation physics.

Modeling optimization of test patterns used in de-embedding method for through silicon via (TSV) measurement in silicon interposer

Abstract: In this paper, the electrical performance of the test patterns used in the de-embedding method for TSV characterization was studied thoroughly. For all test patterns, full wave models were built and then analyzed based on simulated electrical performances. Equivalent circuit model analysis and parametric study results of the test patterns further demonstrate the accuracy of the full wave models. Furthermore, Scanning Electron Microscopy (SEM) measurements were taken for all the test patterns, and full wave models were optimized based on the measured dimensions. Finally, the response of the TSV pair was obtained by de-embedding the pads and traces from the TSV pair simulation with the test fixtures. Good agreement between the de-embedded results with analytical characterization and the full-wave simulation for a single TSV pair was achieved.

An equivalent circuit model for the wire-to-surface junction based on method of moments

Abstract: A modified wire-to-surface junction basis function is proposed in this paper in order to facilitate the extraction of an equivalent circuit model for the wire-to-surface junction. The circuit extraction is based on an MPIE formulation. The extracted circuit model has been validated by the traditional EFIE formulation.

Front delay based causality for network parameters

Abstract: In the present work different methods for delay causality checking and/or enforcing are described. Group delay, phase delay and front delay concepts are discussed and front delay usage for causality checking is suggested. Front delay is approximated as a minimum of a phase delay in the given frequency range for band-limited transfer function. Since measured data usually misses DC values, simple and accurate method for DC extrapolation is offered.

Characterizing EMI radiation physics corresponding to distributive geometry features using the PEEC method

Abstract: The reduction of electromagnetic radiation and couplings is a fundamental issue for electromagnetic compatibility (EMC) and electromagnetic interference (EMI) issues. Even though they represent distributed sources, radiation physics was seldom mapped to the geometry of the structure. In this paper, we develop a new approach based on PEEC to calculate the distributed sources for radiation and the couplings. With this approach, the radiated power from each segment as well as the transferred power between each part is evaluated. Furthermore, the physical meaning of the resultant power is interpreted. It is known that currents curved structures, bents, and other discontinuous and truncated structures cause significant radiation. The radiation from each part can be quantitatively analyzed. This method can be used to physically interpret and predict which features and structures have a small or a large impact on radiation. This provides powerful insight for diagnosing of radiation and couplings. Hence, this can be an important tool for product optimization's for EMI designs.

Several major methods for OTA performance testing of mobile terminal

Abstract: Several major methods for Over the Air (OTA) performance measurement of wireless devices are presented, detailed and compared in this paper, the power-stepping down method defined in the Cellular Telecommunications and Internet Association (CTIA) test plan [1], the RSS-based method and the RSS-curve based method proposed in [2–4], and the transmit-receive co-frequency based method. The derivations of the theoretical foundations for all methods were detailed and the results given by all methods were compared in this paper. Those methods are suitable for receiver sensitivity measurement of single input, single output radio systems such as cellular communication, WiFi, ZigBee and Bluetooth systems.

Inductance extraction for physics-based modeling of power net area fills with complex shapes and voids using the plane-pair PEEC method

Abstract: Identifying the dominant inductance in power distribution network design for multi-layer printed circuit boards that use power net area fills is essential. The plane-Pair partial element equivalent circuit method is used herein to extract a lumped inductance suitable for a physics-based circuit model for power net area fills. The method is being applied for evaluating inductance for irregular geometry with cutouts and holes.

Differential probe characterization

Abstract: In this paper, a novel probe without ground pins is proposed for differential signal measurement. An effective model for the differential probe is built in CST based on measured dimensions. To evaluate the electrical performance of the differential probe, a 4-port measurement is performed for a 1 inch differential pair using the probes. Simulation and measurement results match closely which further verifies the accuracy of the simulation model of both the differential probe and PCB under test. Guidance for launching footprint optimization of the differential probe can be extracted based on the sensitivity analysis results in terms of signal pad size, ground via size and ground pad size of the differential probes. Furthermore, loop inductance of the differential probe is evaluated from both 1-port measurement and simulation results.

Transient simulation for power integrity using physics based circuit modeling

Abstract: A transient simulation analysis is proposed for printed circuit board (PCB) power distribution network (PDN) by using physics based circuit model. The PCB PDN is divided into different blocks. Different modeling methods are used to provide physics-based circuit models for each block. Then, Hspice simulation is used to do transient simulation for the PCB PDN based on the circuit.

Discrete Hilbert Transform based delay causality enforcement for network parameters

Abstract: Causality is one of the important properties for quality check of network parameters. Discrete Hilbert Transform (DHT) based delay causality checking and/or enforcing method is discussed in the present paper. DHT based causality checking/enforcing algorithm is known but is not widely used in applications. Comparison analysis between DHT based delay causality and other causality checking algorithms is given and advantage of the DHT based algorithm is discussed. Front delay is used for delay causality definition. Several methods for front delay estimation are suggested. Delay causality is checked and enforced for different test cases using the proposed methodology.