Bipolar transistors

Which expression gives the DC current gain hFE of a bipolar transistor? (IC: collector current, IB: base current, IE: emitter current)

  1. AIB / IC
  2. BIC / IB
  3. CIE / IC
Show answer and explanation

Answer: B. IC / IB

hFE is the DC current gain in the common-emitter configuration: hFE = IC / IB. It shows that a small base current controls a large collector current, and for typical small-signal transistors it ranges from several tens to several hundreds.

Practice this topic Back to topic

More Bipolar transistors questions

  1. What is the main reason for making the base of a bipolar transistor thin?
  2. When a bipolar transistor is used as a switch, which operating region corresponds to the on state?
  3. How does the phase of the output voltage of a common-emitter amplifier compare with the input voltage?
  4. What is the main reason for making the emitter of an NPN transistor more heavily doped than the base?
  5. What is the approximate common-emitter current gain β of a bipolar transistor whose common-base current gain α is 0.99?