An equivalent two terminal model based on the Thevenin equivalents describes the common mode (CM) currents on the input and output side of two widely used types of dc-to-dc power converters—buck and boost. Thus, it describes a nonlinear circuit by a linear equivalent circuit. The maximized spectrum of the CM currents is extracted for converters with stochastic signals using a novel characterization procedure. The extracted Thevenin model is used in co-simulation combined with a full-wave electromagnetic solver to predict the radiated emissions from the system consisting of the shielded dc–dc converters with attached cables and a DC brushless motor as load. The results using the terminal model agree well with the measurements providing that the actual CM loads are within the range of CM loads used while obtaining the Thevenin equivalent circuit.

Creating an equivalent field source is an efficient method for predicting radiated emissions from IC structures. In this paper, the maximum radiated emissions for a heat-sink/IC structure is predicted by creating an equivalent source from the measured electrical field (E-field) in the gap between the heatsink and IC. The E-field is detected by an E-field probe made of an open coaxial cable coated with absorbing material. A numerical model is built in the computer simulation technology microwave studio to obtain the maximum radiated field, where the measured E-field is used as a source to excite the heat-sink model. The evaluated maximum radiated field is in good agreement with the measured value; the error is within 7 dB up to 40 GHz for the source with phase, and 7 dB up to 10 GHz for the phaseless measurement.

Performance of electromagnetic interference (EMI) filters in power-electronics applications is limited by the parasitic coupling between the components of the filters and the self-parasitic of each component. While these parasitic effects can be partially taken into account on the circuit level, it is difficult to estimate their values. In this article, a full-wave modeling methodology is proposed to predict the performance of a complete EMI filter up to 1 GHz. Following the proposed methodology, the mutual couplings among the EMI filter components are taken into account as well as the self-parasitics of each individual component. Experiments and simulations are carried out to validate the modeling methodology. A self-parasitic cancellation technique is also applied to demonstrate the benefits of three-dimensional modeling methodology in EMI filter design.

Frequency-dependent electrical properties of dielectric materials are one of the most important factors for high-speed signal integrity design. To accurately characterize material's dielectric loss tangent (tanδ) after multilayer printed circuit board fabrication a novel method was proposed recently to extract tanδ using coupled striplines’ measured S-parameters and cross-section geometry. By relating modal attenuation factors to the ratio between the differential and common mode per-unit-length resistances, the surface roughness contribution is eliminated and the contributions of dielectric and conductor loss are separated. Here, we specifically decided to avoid using any physical dielectric model in the extraction algorithm in order to eliminate a need for any a priori information about dielectric behavior. Further analysis and improvement of the tanδ extraction approach is presented in this article. To evaluate the accuracy of the extraction, the impact of errors due to de-embedding, vector network analyzer measurement, and two-dimensional solver's calculation are taken into account by a statistical error model. A confidence interval of extracted tanδ is provided. To describe the frequency dependence of tanδ, a two-term Djordjevic model is proposed to fit the extracted tanδ curve, which guarantees causality and gives better agreement with measured insertion loss compared to the traditional Djordjevic model.

Common-mode (CM) noise on differential signals can be suppressed by planar electromagnetic bandgap (EBG) technologies. In this study, two new CM filter structures were designed, fabricated, and measured. The filters are based on a previously proposed geometry, a “sandwich-type” EBG structure that resonates at the desired filter frequency; however, the new filters are placed on the top of the PCB as a surface-mount component, instead of being implemented within the PCB stackup. Stripline and microstrip versions of the surface-mount filter are considered. The filters can be easily removed and substituted with another one that is designed to filter a different frequency but maintains the same footprint and external dimensions. In addition, the surface-mount filter allows us to incorporate dc blocking capacitors into the microstrip version of the filter, thus providing two functions in one package. The total radiated power (TRP) of the implemented filter is investigated and discussed. RF absorbing material and traditional shielding are considered to reduce the TRP.

In this paper, a method is proposed to calibrate a probe by placing it into a known field and referencing its output voltage to the known field. A transmission line is a convenient structure for creating such a known field. This paper presents the effect of the inhomogeneous medium on the near-field generated over a grounded coplanar waveguide (GCPW) printed circuit board (PCB) and reports the field pattern over the GCPW. GCPW PCBs are used to determine the probe factor for near-field scanning applications. A near-field scan is performed to visualize the near-field sources over a device under test (DUT). The near-field is measured by using E- and H-field electromagnetic interference probes. The output of these probes is a voltage and using the probe factor, the field present over the DUT can be determined. To calculate the probe factor, the near-field strength needs to be known using the 3-D simulation. GCPW creates a quasi-TEM field. The effect of non-TEM modes is easily underestimated, such that non-TEM fields prevent the user from determining the unwanted field suppression of probes at higher frequencies.