A novel technique for concurrent on & off - board EMI analysis of mixed RF-digital circuits via hybrid scattering patterns

Abstract

We propose a hybrid scattering parameter matrix for concurrent on & off board EMI analysis of mixed RF-digital circuits. To start with, we first consider on-board EMI effects on digital circuits, particularly on an inverter to show the vulnerability of digital devices to RF interference and investigate both system and device level upsets due to adjacent EMI sources on printed circuit boards (PCBs). Next, we review port analysis technique to show the applications of S-parameter matrix for on-board EMI/EMC analysis. Subsequently, we extent the port analysis method with hybrid S-parameters to account for external field coupling to RF-digital circuit boards. In this context, we introduce a novel method in the frequency domain to circumvent CPU bottlenecks associated with time domain methods and yields increased accuracy as compared to transmission line theory. To do so, we present additional hybrid S-parameters that establish a link between the existing board ports and external plane wave. Thus, we can handle both on-board and off-board EMI problems simultaneously. The new hybrid S-parameter matrix is easily integrated into circuit solvers such as HSPICE and advanced design system (ADS, Agilent Technologies) and also allows both time domain and harmonic balance simulations of non-linear RF-digital components via broad-band network characterization. The proposed method was validated with full wave solvers and implemented for susceptibility analysis of an inverter, residing inside a metallic box, subject to a strong plane wave.