In fully CMOS digital integrated systems, switching activity of logic gates is the source of the so-called "digital
noise". Together with interconnections parasitics, digital switching noise is known to cause "bouncing" effects,
i.e. oscillations of on-chip supply and bias voltages, which can remarkably degrade overall system performance.
Digital switching is a completely deterministic process, depending on both circuit parameters and input signals.
However, the huge number of logic blocks in a digital integrated system makes digital switching a cognitively
stochastic process. Therefore, logic transition activity can be analyzed using a stochastic approach. In this
paper, we model the digital switching current as a stationary shot noise process, and we derive both its amplitude
distribution and its power spectral density.