Nonlinear analysis of noise in static and dynamic translinear circuits

For translinear filters, or log-domain filters, calculation of the maximal signal-to-noise-ratio, an important filter specification, is not trivial, due to the inherent companding behavior and the nonstationary nature of the transistor noise sources. To address this issue, a nonlinear noise analysis method is proposed. Based on large-signal calculations, expressions for the first-order noise and signal-noise intermodulation terms are computed. The procedure is generally applicable both to static and dynamic translinear circuits, as illustrated by a number of generic examples.