DPI set-up for ICs with differential inputs

This paper introduces a new Direct Power Injection (DPI) set-up used to characterize the conducted immunity of integrated circuits (IC) with differential inputs. It allows injecting common-mode, differential-mode signals or any combination of both. For a given kind of injection, it is necessary to calculate power and phase-shift at generators. To do so, an analytic model is developed based on S-parameters of all blocks involved in the set-up including the IC. This model is validated by simulation under PSpice and by measurement in [1 MHz - 800 MHz] band for pure common-mode and pure differential-mode injections. With this set-up, IC immunity can be characterized as functions of common-mode and differential-mode voltages versus frequency.