UBC Theses and Dissertations
Spectral distribution of noise Bain, William Arthur
An apparatus for the measurement of noise as a function of frequency is described. This apparatus has been used to determine the spectral distribution of the excess noise caused by the flow of a d-c. current through a resistance. The samples used for the experiments were a zinc oxide semiconductor and two metal layer resistors. The frequency region investigated was from 10 kc. to 400 kc. It was found that the excess noise in the ZnO semiconductor obeyed a 1⁄(ν₂)law at room temperature while at lower temperatures (solid CO₂ and liquid nitrogen) it was proportional to 1/ν at low frequencies and 1⁄(ν₂) high frequencies. The excess noise in the metal layer resistors was proportional to 1⁄ν at room temperatures while at 100°C there was a marked deviation from this law in the direction of a 1⁄ν₂ dependence for high frequencies. The measurements show that the 1⁄ν law gradually changes to a 1⁄ν₂ law at high frequencies in accordance with the theory proposed recently by Dr. A. van der ziel. They also indicate that the correlation times involved are a function of temperature; the exact nature of this dependence has yet to be determined.
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