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Abstract: Fast switching signals drive MOSFET into non-quasi-static operation, causing significant charging current in both on-state and off-state. Since MOSFET can be worked as a varactor in RF circuits, the modeling in the off-state is important. In this paper, a compact model is developed to model the fast-switching behavior of transistors in both states. Instead of solving the continuity and drift–diffusion equations, the model reduces the distributed network into a lumped circuit model, which is more compatible with the framework of compact model. The proposed model has been implemented in conjunction with the BSIM model and has been shown to be valid from the accumulation to the inversion. The model is developed independently from the existing I–V and C–V models and can be applied to any advanced model besides BSIM. [Copyright &y& Elsevier]

Abstract: The impacts of base-to-emitter spacer thickness on the unity gain frequency (f T), base resistance (r B), base collector capacitance (C BC) and maximum oscillation frequency (f max) of a bipolar junction transistor (BJT) are studied. Using the extracted Y-parameters from a simulated device with structural parameters calibrated to an actual process, the resulting f T and f max with different spacer thickness is reported. A tradeoff between peak f T and f max is observed and the process window to obtain high f T and f max is proposed. [Copyright &y& Elsevier]

This paper describes the impact of the distributed RC effect in the intrinsic base region on the modeling of the output noise spectral density of a bipolar junction transistor. Simplified expressions to convert the distributed noise models to an improved hybrid-π model with the new equivalent noise sources are proposed. The accuracy of the new model has been verified by circuit simulations. Based on the new model, a noise analysis is done. The simulation results are compared with one by the conventional model. From this, the sensitivity of the noise parameters to the distributed RC effect is studied. [Copyright &y& Elsevier]

Abstract: Objective: The purpose of this study was to determine the normal range of spleen size in an adult African population, and compare the findings to published data to determine any correlation with ethnicity. Materials and methods: Three hundred and seventy-four African adults without conditions that can affect the spleen or splenic abnormalities were evaluated with ultrasonography. Spleen length, width and thickness were measured and spleen volume calculated. Spleen size was correlated with age, gender, height, weight, and body mass index. Results: The mean spleen volume was 120cm3. Spleen volume correlated with spleen width (r =0.85), thickness (r =0.83) and length (r =0.80). Men had a larger mean spleen volume than women. No correlation was found between spleen volume and age, weight, height, or body mass index. Conclusion: Mean spleen volume in African adults is smaller than data from Western sources, and cannot be explained by difference in body habitus. [Copyright &y& Elsevier]