This paper presents a tutorial treatment of the fundamentals of noise in solid-state analog electronic circuits. It is written for upper division students and practicing engineers who wish to gain a basic knowledge of the theory of electronic noise and techniques for low-noise circuit design. The paper presents an overview of noise fundamentals, a description of noise models for passive devices and active solid-state devices, methods of calculating the noise performance of amplifiers, and techniques for minimizing noise in circuit design. The theory and methods are applicable to both discrete and integrated circuits.>