High power EMI on digital circuits within automotive structures

This paper considers the impact of high power electromagnetic interference on performance of digital electronics, more specifically timer, used for controlling spark plug sequence in an automobile. We carry out measurements on a commercially available timer to observe soft and hard upsets and identify important circuit and interfering signal parameters pertaining to the upsets. We observed that as bias voltage decreases, the device becomes less immune to interference. This implies that EMI effects will become more dominant on next generation integrated circuits since bias voltage drops in proportional to the technology size. Subsequently, we proceed to address a more practical case where a timer inside an automobile is subject to a train of high power Gaussian pulses. For the latter case, not only do we investigate characteristics of the interfering signal such as pulse width and magnitude, but also we study impacts of scan angle (incident angle) since scattering from the automobile highly contributes to EMI interference to the timer. Our analysis suggest that pulse duration and scan angle are critical to assessing EMI effects on the timer operation. Experiments are complemented with an analysis that employs our recently developed hybrid S-parameters approach to integrate numerical EM tools (Method of Moments and HFSS) with circuit tools such as Advanced Design System (ADS). Such approach enables us to address EMI analysis of complex structures housing mixed signal circuits with a high simplicity and flexibility. Implications of our findings are discussed and future work that will lead to a more practical and realistic assessment of EMI on performance of electronic systems is addressed as well.