Low-frequency noise figure and its application to the measurement of certain transistor parameters

Low-frequency noise measurements are shown to provide a convenient and reasonably accurate (±10 per cent) means of measuring r\´_{b}. Their application to the measurement of the factor in the junction law is also described, though the values of obtained from noise measurements do not check accurately with the values of determined by other methods. Experimental determinations of the variation of low-frequency noise figure with emitter-bias current are also presented for several transistor types. The observed behavior suggests that the principal source of noise in low-noise transistors may be in the emitter-base transition region instead of on the base surfaces where it is placed in presently accepted noise models.