Modeling strategies for estimating and suppressing electromagnetic interference and improving power integrity
"Decoupling capacitors are used to suppress high-frequency noise in power distribution networks. The inductance associated with a mounted decoupling capacitor can vary by 26% depending on characteristics of the printed circuit board. Here, simple and accurate inductance models of 2- and 8-terminal capacitors including connections to the power and return plane are developed. Circuit models of the capacitors and layout are created using the partial equivalent element circuit method which provide options for circuit-level simulations as well as analytic estimation of inductance. The circuit solution matches results from the full-wave simulation model within 9% for the 8-terminal capacitor and within 15% the for the 2-terminal capacitor. System-level radiated emissions from a harness are primarily caused by common-mode currents on the harness. An approach is needed to predict system-level emissions early in the design process based on a relatively simple component-level measurements. A prediction technique estimates equivalent common-mode source voltages and impedances based on component-level measurements, which can be used to predict the common-mode current on a harness of arbitrary length or characteristic impedance. Shielding the victim or isolating the noise source can suppress electromagnetic interference. Numerical and analytical methods can accurately estimate shielding effectiveness if the conductivity and permeability of the shielding material is known. A measurement process for obtaining equivalent material properties at low frequencies (from than 0.01-1 MHz) is proposed. Comparison of measured and simulated shielding estimated using material properties found with this process agree within 1.6 dB"--Abstract, page iv.
Missouri University of Science and Technology
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