A BJT has the following values: td = 20 nS, tr = 20 nS, ts = 150 nS, and tf = 60 nS. What is the upper cutoff frequency for the device in any switching application?
A) 6.7 MHz
B) 4 MHz
C) 17.5 MHz
D) 175 kHz

Question

Quizplus · Accepted Answer

The upper cutoff frequency (fT) for a BJT in switching applications can be estimated using the formula fT = 1 / (td + tr + ts + tf). Substituting the given values: fT = 1 / (20 nS + 20 nS + 150 nS + 60 nS) = 1 / 250 nS = 4 MHz. However, the correct calculation should consider the switching time (ts) as the dominant factor, leading to fT = 1 / (tr + tf) = 1 / (20 nS + 60 nS) = 12.5 MHz, but considering the closest option, 17.5 MHz is the most reasonable choice.

A BJT Has the Following Values: Td = 20 NS