Location of low-frequency noise sources in submicrometer bipolar transistors

Expressions are derived for the low-frequency noise (1/f noise, shot noise, Nyquist noise) in bipolar transistors. Particular attention has been paid to the influence of the internal base and emitter series resistance. The expressions have been compared with experimental results from submicrometer silicon bipolar transistors. It is found at low forward currents that the 1/f noise is dominated by 1/f noise in the base current. At high-forward currents the 1/f noise probably stems from the 1/f noise in the internal base series resistance. How to locate the low-frequency noise sources is demonstrated theoretically by analyzing the results for the common-emitter and the common-collector configurations both at low and high currents and at different values of the external resistances