Review of low-frequency noise in bipolar transistors over the last decade

Experimental studies on low frequency noise in bipolar junction transistors (BJT) including polysilicon emitter, hetero-junction transistors (HBTs) and SiGe HBTs are reviewed. The validity of a new empirical relation between the 1/f noise corner frequency f/sub c/ (the frequency where the 1/f noise and shot noise are equal) and the cutoff frequency f/sub T/ is investigated. The coherence-method to investigate the most dominant low-frequency noise source in the equivalent circuit is described.