Noise equivalent circuit for nonlinear resistors

Abstract

A Gaussian white noise model for passive nonlinear resistors with linear-quadratically approximated I-V-characteristics is suggested. The model is an approximative version of a more precise model that has been obtained from purely thermodynamic, macroscopic considerations. Thus, it may serve as a thermodynamic justification of non-thermodynamic device noise models. Apart from temperature, it only depends on the first two Taylor coefficients of a device's I-V-characteristics. It is independent of further device specific features like shape, size or carrier transport mechanism. It is capable of describing frequency independent types of noise that can be derived from macroscopic, non-quantum considerations: thermal noise and shot noise. It does not comprise 1/f-noise. To test the model it is applied to the shot noise of pn-junction and Schottky-barrier diodes and a tunnel junction as well as to the thermal noise of a JFET and a MOSFET. The results are in full agreement with the standard noise models for these devices, which are usually obtained from device specific microscopic or kinetic models. The model, which comprises Nyquist's theorem as a special case, is a generalization of Nyquist's theorem to linear-quadratic nonlinear resistors.