Effect of base profile on the base transit time of the bipolar transistor for all levels of injection

Comparing the uniform base profile with the exponential base profile in low injection, the uniform base profile gives a lower base transit time for a given base resistance and peak base concentration, while the exponential base profile gives a lower base transit time for a given base resistance and base width at large base widths. At high injection the uniform base profile always gives the minimum base transit time. The uniform base doping is the optimal base profile for BiCMOS circuits in which the bipolar transistors are operated under high injection.<
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