An analytical all-injection charge-based model for graded-base HBTs

Abstract Current transpsort and charge concentration in graded base heterojunction bipolar transistors (HBTs) have been investigated, and an all injection charge-based model suitable for implementation in computer aided design tools has been developed. In this model, injected current, charge and recombination current components are formulated for all levels of injection. Base grading effect on current components, current gain and cutoff frequency in the high current regions are studied. This model is a general model which is also valid for modeling ungraded base HBTs. The model is found to be in good agreement with the experimental and numerical results.

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