Bipolar transistors

Which correctly describes the difference in how bipolar transistors and MOSFETs are controlled?

  1. AA bipolar transistor is controlled by base current, while a MOSFET is controlled by gate voltage (almost no DC gate current flows)
  2. BA bipolar transistor is controlled by light and a MOSFET by temperature
  3. CBoth are controlled by a gate voltage, and no DC current flows into the control terminal
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Answer: A. A bipolar transistor is controlled by base current, while a MOSFET is controlled by gate voltage (almost no DC gate current flows)

A bipolar transistor is a current-controlled device that controls the collector current by passing a current into the base. A MOSFET's gate is isolated by an insulator; it is a voltage-controlled device whose channel is controlled by the field from the gate voltage, and almost no gate current flows in steady state.

  • A. Correct. It is the difference between current control and voltage control.
  • B. Both are controlled by electrical signals.
  • C. A bipolar transistor needs base current for control.
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More Bipolar transistors questions

  1. 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.)
  2. What is the state of the junctions when a bipolar transistor is in the saturation region?
  3. 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?
  4. What does the load line drawn on the output characteristics of a transistor amplifier represent?
  5. Which value is closest to the maximum power efficiency of an ideal class B push-pull amplifier?