Rusty Bolt EMC Specification Based on Nonlinear System Identification

There is a recognized interference problem in dense electronic platforms due to harmonic and inter-modula­ tion interference caused by the nonlinearity of metalinsulator-metal (MIM) or metal-oxide-metal (MOM) junc­ tions in the coupling paths between collocated trans­ mitters and receivers. Although the surfaces involved can be distributed in nature, the junction is colloqui­ ally called the "rusty bolt". This paper examines the identification of the lumped parameter rusty bolt non­ linear transfer functions (NLTFs) and their use in pre­ dicting electromagnetic compatibility (EMC) specifica­ tion parameters such as intermodulation and harmonic distortion. Results illustrating the procedure are presented. The errors which can be encountered in the identified parameters and in the predicted EMC speci­ fication parameters are examined. It is concluded that the EMC parameters up to the fifth order can be predicted with good quality provided that the number of poles is identified correctly and that the identification errors are reasonable (say less than 30 percent).