Flicker noise in transistors

Measurements of the noise voltage appearing at the ac open-circuited emitter of a transistor with its collector ac grounded and with both an external base resistance and the operating point as parameters can be used to study the location of flicker-noise sources in transistors. A general flicker-noise model is assumed. It is shown by this method of measurement that for many modern transistors the flicker-noise sources are adequately represented by a single noise current generator connected in parallel with the emitter-base junction. The method permits evaluation of the magnitude of both the correlated and uncorrelated parts of a possible collector-base flicker-noise current generator as well as measurement of the emitter-base generator.