Microwave noise of Si/Si0.6Ge0.4 heterojunction bipolar transistors

The microwave noise of Si/SiCe HBTs was characterized and modeled using a high-frequency T-equivalent noise circuit model. A 6 finger 2x15 mu m(2) HBT showed a minimum noise figure of 2.26dB with an associated gain of 12.7dB, measured at 8 GHz under I-C=14mA and V-CE=3V bias condition. Bias, frequency and HBT geometry dependent noise measurements were also performed. It was found that the 6 finger 2x15 mu m(2) HBT has the best noise performance among the characterized devices. Moreover, it was revealed that minimum noise figure reaches a minimum at a medium collector current. Finally, a simple all physical high-frequency T-equivalent noise model was extracted from the measured S-parameters and noise data and was used for the study of noise dependence on different HBT equivalent circuit parameters.