Modeling of the low-frequency base resistance of single base contact bipolar transistors

The current and geometry dependence of the base resistance of single base contact (SBC) bipolar transistors is accurately modeled by extending the simple analytical formulas given by T. Ohzone et al. (1985). The results show that SBC transistors only seem to be useful if the ratio of emitter width b to emitter length l is larger than about 1/5. Of course, this limit depends on technology and circuit application