Bipolar transistors

What is the typical base-emitter voltage VBE of a silicon bipolar transistor operating in the active region?

  1. AAbout 0.6 to 0.7 V
  2. BAbout 0.1 V
  3. CAbout 3 V
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Answer: A. About 0.6 to 0.7 V

The base-emitter junction is a silicon PN junction, so the voltage across it when conducting forward current is about 0.6 to 0.7 V. In circuit design, VBE ≈ 0.7 V is often used for calculations.

  • A. Correct. For silicon it is about 0.6 to 0.7 V.
  • B. At about 0.1 V almost no current flows through a silicon junction.
  • C. About 3 V is far too large for the forward voltage of a silicon PN junction.
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More Bipolar transistors questions

  1. What is the collector dissipation of a transistor operating at a collector-emitter voltage of 5 V and a collector current of 100 mA?
  2. Which correctly describes the difference in how bipolar transistors and MOSFETs are controlled?
  3. In a common-emitter amplifier with transconductance gm = 40 mS and collector resistor RC = 5 kΩ, roughly what is the magnitude of the voltage gain? (Ignore the load.)
  4. What is the state of the junctions when a bipolar transistor is in the saturation region?
  5. When the output characteristics (IC-VCE) of a common-emitter transistor are plotted with base current IB as a parameter, what is characteristic of the active region?