The Johnson limit [1] predicts that due to fundamental material limita
tions, the f(t)BV(ceo) product for Si bipolar transistors cannot excee
d 200 GHz-V. Since this limit ignores many practical components, it sh
ould not be achievable experimentally. In light of the fact that resul
ts reaching this limit have been reported, we have reevaluated such fu
ndamental limits, and have found that this number should be much highe
r.