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Consider the following statements (a) BJT is a current controlled device with high input impedance and high gain band width (b) FET is a voltage- controlled device with high input impedance and low gain bandwidth (c) UJT is a negative resistance device and can be used as an oscillator (d) FET and UJT can be used for amplification Which of the above statements are correct 

Consider the following statements (a) BJT is a current controlled device with high input impedance and high gain band width (b) FET is a voltage- controlled device with high input impedance and low gain bandwidth (c) UJT is a negative resistance device and can be used as an oscillator (d) FET and UJT can be used for amplification Which of the above statements are correct  Correct Answer (b) and (c)

BJT (Bipolar Junction Transistor):

  • It is a current-controlled device
  • The input for BJT is a forward-biased diode, so the input impedance is low (Statement (a) is incorrect)
  • It has higher unity-gain bandwidth.

FET (Field Effect Transistor):

  • It is a voltage-controlled device.
  • It has a high input impedance as the gate is Reverse biased for JFET's and because of the insulating layer in the case of MOSFET's. (Statement (b) correct)
  • It has low gain bandwidth.

UJT (Unijunction Transistor):

  • The device has a unique characteristic when it is triggered.
  • It exhibits a negative resistance characteristic and so it can be employed as an oscillator (Statement (c) is correct)
  • It cannot be used as an amplifier.

Related Questions

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