Nyquist Model based Thermal Noise AnalysisFrom Passive Components to CMOS Circuits

Abstract

The analysis of thermal noise in network components that have resistive properties is presented. Noise analysis, based on the Nyquist model, is calculated as the rms (voltage or current equivalent) noise generated by a transimpedance, which is the concept used by general-purpose circuit simulators like Spice. It shows how this concept is used and understood in RC circuits, and how to evaluate its effect in analog circuits, particularly in the design of CMOS integrated circuits. It is shown that the magnitude of the noise generated by a transistor is not of interest, but the net effect of all sources of thermal noise in circuits and systems, fundamentally, when the miniaturization of the transistor implies reducing the value of the supply voltages. The ultimate purpose of this contribution is to highlight the importance of noise analysis using fundamentals of circuit theory and identify the variables under the designer's control to minimize their effect on the performance of the circuits under development.