Noise

Abstract

This chapter examines noise, another example of cause and chance at work, and an example of the statistical fluctuations in the response arising from random events. Approaches to understanding randomness embedded in signals are discussed along with the notion of ergodic behavior, autocorrelation and the use of the Wiener-Khintchin theorem. Fluctuations and noise in semiconductors are analyzed by exploring charge transport between plates under scattering. The quantum and thermodynamic links at resonance are emphasized. The Nyquist relationship, a very general relationship, is derived. Partition thermal noise under limited channels is explored, and shot noise is discussed. Low frequency noise arising as random telegraph noise due to charge trapping and detrapping is analyzed. Noise in a parameter—resistance, for example—can be due to multiple interactions. An example of this is resistance fluctuation due to mobility and carrier fluctuations, which in many materials can be parameterized through the Hooge parameter.