Thermal and Shot Noise: Analysis in Diodes and Transistors

This lecture discusses the origins and calculations of thermal and shot noise in electronic components, particularly diodes and transistors. It begins by examining the behavior of electrons across a potential barrier, highlighting how the applied voltage affects current flow. The instructor explains the relationship between thermal noise and differential resistance, providing formulas for calculating noise power at zero voltage. The lecture emphasizes the independence of currents in calculating shot noise and demonstrates how thermal noise can be interpreted as a sum of shot noise from both positive and negative currents. Various examples, including Schottky diodes and bipolar NPN transistors, illustrate the principles of noise generation and the impact of voltage on current behavior. The instructor concludes by reinforcing the concept that thermal noise corresponds to the hidden shot noise produced by the currents, regardless of their average cancellation at equilibrium. This comprehensive analysis provides a deeper understanding of noise in semiconductor devices and their implications in optical detection applications.