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
n
in the junction law
p_{e} = p_{n} (e_^{qV/nkT} - 1)
is also described, though the values of
n
obtained from noise measurements do not check accurately with the values of
n
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
1/f
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.