Noise parameter optimization of UHV/CVD SiGeHBT's for RF and microwave applications

This paper demonstrates a predictive noise parameter estimation methodology for UHV/CVD SiGe HBT's which combines ac measurement, calibrated ac simula tion and two of the latest Y-parameter-based noise models: 1) the thermodyn amic noise model, and 2) the SPICE noise model. The bias current and freque ncy dependence of the minimum noise figure, the optimum generator admittanc e, and the noise resistance are calculated using both models and compared w ith measurements. The observed agreements and discrepancies are investigate d using circuit analysis of the chain noisy two-port representation. For th e devices under study, the SPICE model description of thermal noise produce s a better overall agreement to data in terms of all the noise parameters. Experiments on devices with different collector doping levels show that bot h low noise and high breakdown voltage ran be realized with one profile wit hout significantly compromising the ac current gain and the ac power gain.