Measurement and characterization of low frequency noise collector current in 0.13 μm SiGe:C HBTs

This work presents an improved measurement setup to directly measure the collector low frequency current spectral density S_IC of SiGe:C Heterojunction Bipolar Transistors (HBTs) when the base is AC short-circuited. A comprehensive analysis of the obtained results is also provided as well as a SPICE based electrical model. The additional white noise observed at high collector biases is due to the contribution of the emitter/base internal resistance. The 1/f noise exhibits a linear evolution with a 1.7 slope versus I_C and is proportional to 1/√A_e. No evolution of S_IC with emitter periphery P_e was observed. From a comparative study of the different 1/f noise term of S_IC we found that S_IC is mainly associated with the spontaneous fluctuations of the intrinsic collector current.