The variation of the low-frequency noise in polysilicon emitter bipolar junction transistors (BJTs) was investigated as a function of emitter area $(A_{E})$. For individual BJTs with sub-micron-sized $A_{E}$, the low-frequency noise strongly deviated from a $1/f$-dependence. The averaged noise varied as $1/f$, with a magni-$\mathbf{tude \,\, proportional \,\, to} A_{E}^{-1}$, while the variation in the noise level was $\mathbf{tude \,\, proportional \,\, to}\mathbf{found \,\, to \,\, vary \,\, as \,\, A_{E}^{-1.5}}$. A new expression that takes into account this deviation is proposed for SPICE modeling of the low-frequency noise. The traps responsible for the noise were located to the thin $\text{SiO}_{2}$ interface between the polysilicon and monosilicon emitter. The trap's energy level, areal concentration and capture cross-sectionwere estimated to 0.31 $\text{eV}, 6\times 10^{8}cm^{-2}$ and $2\times 10^{-19}\text{cm}^{2}$, respectively.