A Circuit Model for ESD Performance Analysis of Printed Circuit Boards

This paper provides a SPICE-compatible circuit model for characterizing electrostatic discharge (ESD) clamping performance of protection devices mounted on printed circuit boards (PCBs). An equivalent circuit model for a commercial ESD generator is introduced and a simulation methodology of an ESD protection device with non-linear resistance characteristic using voltage controlled current source is described. These models combined to create a full circuit model with a PCB model in a SPICE-like circuit simulator. Comparison results between the simulated and measured are presented to verify the accuracy of the proposed circuit model. A trade-off analysis between the ESD clamping performance and signal integrity with the ESD protection device in high-speed applications is also presented as a case study

A Simple Estimation of TRP and Radiation Pattern for Mobile Antennas using Planar Near-Field Scanning Method

An estimation method for the total radiation power (TRP) and radiation pattern of mobile antennas embedded in mobile phones using a planar near-field scanning method is proposed. The tangential magnetic fields on both front and rear faces of a mobile phone are measured both in magnitude and phase using a dual-probing technique in the time-domain. Moreover, for accurately obtaining the phase information from the measured data in the time-domain, a reliable triggering technique is introduced. The far-field is calculated by using the near-field to far-field transformation based on the equivalent principle and the image method. The calculated TRP and radiation pattern are validated by comparison with the measured TRP and radiation pattern in an authorized anechoic chamber, and good agreement has been achieved

Placement Optimization of Integrated Circuits for Reduced Radio-Frequency Interferences in Mobile Devices

In this article, an optimization procedure for the placement of integrated circuits (ICs) for reduced radio-frequency interference (RFI) in mobile devices is presented. The concept of a power conversion factor (PCF) is introduced to quantify the near-field radiation of ICs based on near-field measurement techniques. For PCF extraction, equivalent source antennas are designed to represent the radiation chracteristics of ICs. In addition, the concept of a power transfer function (PTF) is also introduced to characterize the near-field propagation from RFI noise sources to the built-in antennas in mobile devices. From the combination of the PCFs and the PTFs, a spatial near-field specification of ICs for reduced RFI is proposed. Based on the proposed specification, the application example of an optimized IC placement in mobile platform design is presented

A Novel Shielding Effectiveness Matrix of Small Shield Cans Based on Equivalent Dipole Moments for Radio-Frequency Interference Analysis

A definition of a shielding effectiveness (SE) matrix for small shield cans used to suppress intra-system noise coupling in mobile devices is proposed. Assuming shield cans enclosing a noise source can be modeled as equivalent dipole moments along with integrated circuits (ICs), a new SE matrix for radio-frequency interference analysis is defined as a ratio of equivalent dipole moments with and without a shield can. The equivalent dipole moments are experimentally extracted using a GTEM cell and two types of probes (monopole and loop), which mimic well the radiations of ICs. Furthermore, the estimation of suppression of noise coupling to an antenna using the proposed SE matrix is successfully validated through numerical simulations

Assessment of Integrated Circuits Emissions with an Equivalent Dipole-Moment Method

An appropriate integrated circuit (IC) evaluation early in the design stage is essential to ensure timely development of mobile devices with a satisfactory total isotropic sensitivity (TIS), a figure of merit to measure radio-frequency receiver sensitivity. An IC evaluation method based on equivalent dipole-moment source using the transverse electromagnetic mode (TEM) cell is proposed and experimentally investigated in terms of correlation of measured TIS with two existing IC emission measurement methods: the TEM cell method (IEC 61967-2) and the near-field scan method (IEC 61967-3). In addition, a cost-effective and reliable test scheme is introduced so the three approaches can share a single common test board to avoid potential hardware-to-hardware deviation. Measurement results on three software-controlled operation states are compared with respective TIS measured in an anechoic chamber. The best correlation was obtained in the proposed equivalent dipole-moment-based evaluation method and the limitations of the two previous methods are discussed

MoM-Based Ground Current Reconstruction in RFI Application

A method of moment (MoM)-based current reconstruction method is proposed to estimate the surface current density on the ground plane. Current continuity property is automatically enforced with Rao-Wilton-Glisson basis function. Both the least square method and the optimization method are utilized to solve the inverse problem and obtain the ground current. The proposed optimization method is successfully validated with numeric simulations and also a real-world measurement example. The reconstructed current distribution on the ground plane is further used in a typical radio frequency interference (RFI) example to perform RFI estimation and provide guidelines for RFI design. The proposed MoM-based ground current reconstruction method can be valuable to estimate and debug RFI issues in early design stage

MoM Based Current Reconstruction using Near-Field Scanning

Multiple digital ICs sharing ground plane have potential problems of ground noise interference to each other. Current distribution on the ground plane can introduce intra-system EMC issues, which can possibly result in receiver desensitization issue in wireless devices. In this paper, a method of moment (MoM) based current reconstruction method is proposed to estimate the current on the ground plane. This method requires phased resolved near field data for accurate current reconstruction. The proposed method is validated by a numerical example. The current reconstructed from the proposed method is compared with the current from the simulation tool. The difference is within 3.5 dB which is acceptable for most engineering practice

Measurement Validation for Radio-Frequency Interference Estimation by Reciprocity Theorem

This paper presents the measurement validation of reciprocity theorem method for near-field coupling estimation. The overall problem is decomposed into two parts, the first part is called forward problem, and the second part is called the reverse problem. For forward problem, the noise source IC is modelled by physics-based dipole moment model with data obtained from a near-field scanning plane, then the tangential E and H fields on a Huygens\u27s box enclosing the victim antenna are calculated by analytical expression. In reverse problem, the victim RF antenna is modelled in full-wave simulation tool and the tangential E and H field are obtained by simulation. With tangential E and H field obtained in forward problem and reverse problem, the coupled noise power is then estimated by reciprocity theorem. The estimated noise coupling power is compared with measured power at the victim antenna port with IC excited. The difference is within 5dB which is acceptable for engineering practice

Application of Dipole-Moment Model in EMI Estimation

This paper used magnetic near fields to extract the dipole-moment model to represent the real radiation source. This method prevents the measurement of electric fields so that the scanning time and points are saved significantly. These equivalent dipole-moment models can take the place of the real radiation source in the full-wave simulation tool. The electromagnetic interference between the real source and victim structures are well predicted in the simulation by the dipole-moment model. This is validated by a numerical example in this paper

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

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\u27s 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\u27s surface can be obtained. With these two groups of the fields on the Huygens\u27s 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