Bipolar Junction Transistor (BJT) Viva Questions and Answers

Viva Questions and Answers on Bipolar Junction Transistor Experiment

1. Briefly discuss about a transistor?

We can simply say that, a “junction transistor is simply a sandwich of one type of semiconductor material between two layers of the other type”. A transistor has three terminals namely emitter, base and collector. A transistor is a current sensing device. Transistor was developed in the year 1948 at BELL laboratories. A transistor can be seen as two p-n junction placed back to back. The emitter is heavily doped, while the base is lightly doped. The collector is moderately doped. A transistor can be considered as the heart of electronic products. It is almost used in all electronic devices. There are mainly two types of transistors namely, pnp and npn transistors.

2. Discuss about a Bipolar Junction Transistor (BJT), explain about its terminals, types, and mention which type is better? Justify your answer?

Field Effect Transistor (FET) Viva Questions and Answers

Viva Questions and Answers on Field Effect Transistor Experiment

1. Explain the differences between a BJT and a JFET and compare them?

The main difference of BJT (Bipolar Junction Transistor) and FET (Field Effect Transistor) is BJT is a current controlled device, while FET is a voltage controlled device (Control by the change in voltage at the gate terminal).  The current in BJT is produced due to the movements of both electrons and holes (current flow is due to both majority and minority carriers). In FET, the current is produced due to either electrons or holes (current flow due to majority charge carriers only). The main advantage of BJT and FET is that in electrical and electronics circuits, both devices can be used as switches and amplifiers. As compared to BJT, FETs are faster switching devices. In BJT, the Current-Voltage (I-V) characteristics are linear, but in FET, it is non-linear.  For radiation, FET is good, while BJT is sensitive. The noise effect is more in BJT as compared to FET.