Noise analysis of externally linear systems

Noise analysis in externally linear time-invariant systems is complicated by the facts that noise sources may not be stationary and the relationships between the noise sources and the output are generally nonlinear. In this paper, we present a general noise analysis method which can be used to speed up repetitive noise calculations for a given system, and, most importantly, for theoretical investigations of its noise behavior, possibly leading to low-noise design techniques. A current mode syllabic companding and two log-domain filters are analyzed as illustrative examples