Equivalent Circuit for I/O Electrical Fast Transient Testing

The focus of this paper is a linear Thevenin-equivalent model with time-varying sources to capture the voltage waveforms induced in an I/O cable during Electrical Fast Transient (EFT) testing. The model enables accurate prediction when the cable is connected to any linear/nonlinear circuitry - such as TVS diodes, common mode chokes, and ESDIEFT protection circuitry. Due to the extremely low coupling through a well-shielded cable, this work utilizes direct measurements with a high Common Mode Rejection Ratio (CMRR) optically-isolated oscilloscope probe. A unique linear least squares technique to fit these measurements to an HSPICE model was developed. The model was employed to investigate the effectiveness of common platform solutions for EFT issue and show the development of an example silicon-level specification for EFT.