Comments on "On the base profile design and optimization of epitaxial Si- and SiGe-base bipolar technology for 77 K applications. II. Circuit performance issues"

For the original paper see ibid., vol. 40, p. 542-555 (1993). The base transit time of the trapezoidal Ge base profile for the SiGe bipolar transistor has been evaluated. The analytical equations derived in the aforementioned paper result in significant error as the trapezoid profile is close to uniform Ge profile. In this work accurate analytical equations are derived. Comparisons between the present analytical predictions and previous published results are given.