Broadband Noise Modeling of SiGe HBT under Cryogenic Temperatures

In this paper, we present a detailed analysis and modeling of the broadband noise parameters for a 200 GHz SiGe HBT technology under cryogenic temperatures. A transit time based noise model is used to accurately predict the fundamental noise parameters using the measured Y-parameters of the device at 85 K. Analytical equations are presented which represent the noise parameters as a function of device parameters and temperature. The frequency and bias dependence of the noise parameters are modeled using this "transit-time" model at room temperature (300 K) and 85 K.