Transversal and longitudinal noise and their coherence in MOST

The thermal and 1/f noise have been studied in MOSTs with side contacts along the channel. In difference biasing conditions, the distribution of the transversal noise in the channel has been explained in terms of the local values, including surface concentration, noise parameter, and mobility. Below saturation, the calculations are in good agreement with the observed experimental data. At saturation, the 1/f noise source strength seems to be nonuniform, along the channel, and the simple model deviates from experimental results. Possible reasons for this are discussed. The observed transversal noise and the coherence of longitudinal noise indicate that 1/f noise is uniformly generated through the channel in the ohmic region. However, there is no proof of the hypothesis that temperature fluctuation is the origin of the 1/f noise. A simple expression is derived to estimate the ratio of transversal to longitudinal noise in terms of channel geometric parameters. For MOSTs biased in the ohmic region at high gate voltage there is good agreement between experimental and calculated results.<
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