Transmission line routing for reduced external field disturbance

When immersed in a disturbing electromagnetic field, electronic systems are subject to interference due to the energy injected by the external field into the system through the electronic units and, especially, through the transmission lines connecting units one another. The issue of reducing the unwanted energy injection through connecting transmission lines is addressed in this contribution from the point of view of the routing, i.e. of the disposition of the connecting lines that minimizes the injection. The problem is formulated as an optimization problem, dealt with by the simulated annealing minimization technique combined with an efficient way of computing the field coupling to the lines. Results are reported for various cases, and the relation between the characteristics of the interfering field and the efficiency of the reduction is discussed.     

Assessment of digital integrated circuit electromagnetic emissionbased on radiated power evaluation

This paper deals with the assessment of digital integrated circuit (IC) electromagnetic emission (EME), and concentrates on the specific aspect of EME of long external wiring, driven by IC input-output pins. In particular, the contribution of single IC pins is investigated by analyzing the structure composed of an IC output driver connected via a microstrip line to a receiver. A transmission-line model is used, and an approach based on the concept of radiated power is applied to the characterization of single-pin IC EME in terms of external-wiring radiation effects. By the analysis of typical driver-wiring configurations, it is shown that the spectrum of the driver output current is the quantity of interest, and that the use of wiring with smaller characteristic impedance leads to larger radiated power. The use of a specific test setup (IEC 61967-4-150-Ω direct coupling method) for the experimental assessment of single pin IC emissions is also considered. Frequency-dependent setup effects are experimentally ascertained via a scattering parameter characterization, and definition of suitable circuit functions. An estimate of the degree of correlation between voltage measurements foreseen by the test procedure and the total power radiated by the loading network of an IC driver is derived     

Efficient transient analysis of nonlinearly loaded low-loss multiconductor interconnects

The combined time- and frequency-domain analysis of nonlinearly loaded low-loss interconnects is addressed. We show that a variety of interconnects commonly employed in different technological applications are characterized by transfer functions, whose impulse responses have a fast initial-time structure (due to the skin effect) and a slow long-time part (due to ohmic losses). The dependence of the impulse response structure on the line parameters is discussed, along with the exact analytical solutions valid for the skin effect and ohmic losses, separately. A piecewise linear approximation of the transient functions with nonuniform sampling is proposed as an effective method to obtain high accuracy at low computational costs. Various numerical examples are used to validate the effectiveness of the proposed representation, and to show that a matched characterization of the line must be adopted in order to avoid numerical artifacts.     

Closed-form transmission line model for radiated susceptibility in metallic enclosures

This work presents an approximate frequency domain mathematical model based on the transmission line (TL) theory for field-to-wire coupling in a rectangular metallic enclosure. The currents and voltages at the terminations of a TL induced by known electromagnetic (EM) field sources are expressed in closed form. Validity limits and applicability of the model are discussed by comparing the analytical TL-based predictions with the outputs of a full-wave numerical analysis of the overall structure using a three-dimensional finite integration technique. Deviations from the full-wave solution, due to the scattered field from the TL, have been identified, analyzed, and discussed. The proposed analytical model proves to be generally suited for accurate prediction of radiated susceptibility of single-ended interconnections in closed environments.     

EMC prediction model of a single wire transmission line crossing acircular aperture in a planar screen

The structure composed by a wire running above a ground plane and passing through an aperture in a semi-infinite metallic screen is analyzed from an electromagnetic point of view. We assume that the distance between the wire and the ground plane is sufficiently greater with respect to the aperture dimensions and that the latter are small in comparison with the free-space wavelength. A very accurate low frequency solution is obtained by representing the field quantities in a suitable spectral domain and by treating the wire current as a filament current. A transmission line model of the structure, based on the scattering parameter representation for both internal and external excitation, is derived. Then, by use of such a model, analytical expressions for an insertion loss and a signal-to-noise ratio (SNR) are obtained in order to assess the electromagnetic compatibility of the structure     

Statistical piecewise-linear model for transmission linesusceptibility to external noise

Radiated susceptibility of a matched transmission line is described via statistical estimates. Electromagnetic interference is modelled as a plane wave with unknown incidence direction and polarisation. A piecewise-linear frequency-domain model for expectation and standard deviation of load current is derived. Model validity includes line standing-wave region, and extends classical worst-case models based on deterministic assumptions