The correlation resistance for low-frequency noise compact modeling of Si/SiGe HBTs

The measurement of the correlation between the noise generators is a mandatory issue for the low-frequency noise modeling of bipolar transistors, and it is recognized as a very hard experimental task. In the present work, we introduce the concept of correlation resistance and we demonstrate that it can be usefully employed as a guideline for the low-frequency noise modeling in terms of intrinsic noise sources. As a proof of concept, the investigation technique is applied to submicron, BiCMOS-compatible Si/SiGe heterojunction bipolar transistors. It is pointed out that a satisfactory description of the transistor low-frequency noise behavior can be obtained by taking into account noise sources associated with surface recombination/fluctuation in the extrinsic base region.