Title: Phase Noise and Jitter in Digital Electronics,
Abstract: This article explains phase noise, jitter, and some slower phenomena in
digital integrated circuits, focusing on high-demanding, noise-critical
applications. We introduce the concept of phase type and time type phase noise.
The rules for scaling the noise with frequency are chiefly determined by the
spectral properties of these two basic types, by the aliasing phenomenon, and
by the input and output circuits. Then, we discuss the parameter extraction
from experimental data and we report on the measured phase noise in some
selected devices of different node size and complexity. We observed flicker
noise between -80 and -130 dBrad^2/Hz at 1 Hz offset, and white noise down to
-165 dBrad^2/Hz in some fortunate cases and using the appropriate tricks. It
turns out that flicker noise is proportional to the reciprocal of the volume of
the transistor. This unpleasant conclusion is supported by a gedanken
experiment. Further experiments provide understanding on: (i) the interplay
between noise sources in the internal PLL, often present in FPGAs; (ii) the
chattering phenomenon, which consists in multiple bouncing at transitions; and
(iii) thermal time constants, and their effect on phase wander and on the Allan
variance.