Table of Contents
- 1 What is meant by bipolar junction transistor?
- 2 Why transistor is so called bipolar junction transistor why we keep base very thin and lightly doped explain working of NPN PNP transistor?
- 3 How does a Unijunction transistor work?
- 4 Why UJT is called unijunction?
- 5 Why is emitter base junction of a transistor thin?
- 6 What do you mean by reverse active?
What is meant by bipolar junction transistor?
A Bipolar Junction Transistor, or BJT, is a solid-state device in which the current flow between two terminals (the collector and the emitter) is controlled by the amount of current that flows through a third terminal (the base).
Why transistor is so called bipolar junction transistor why we keep base very thin and lightly doped explain working of NPN PNP transistor?
The base region in a transistor is made very thin so that there is a better conduction of majority carriers from emitter to collector through base. The base region in a transistor is doped lightly so that the number density of majority carriers (electrons in p-n and holes in n-p-n transistor) is low. …
How does a Unijunction transistor work?
The Unijunction Transistor (UJT) will act as voltage breakdown device, when the input applied between emitter and base 1 reduces below breakdown value i.e., RB1 increases to a higher value. This shows that RB1 depends on the emitter current and it is variable.
Why is the base in the transistor thin and lightly doped explain?
If base is made thick and highly doped, majority carriers will combine with the other carriers within the base and only few is collected by the collector which leads to small output collector current. Thus in order to have large output collector current, base is made thin and lightly doped.
Why UJT is called unijunction device?
The device has only one junction, so it is called the unijunction device. The device, because of one P-N junction, is quite similar to a diode but it differs from an ordinary diode as it has three terminals. The structure of a UJT is quite similar to that of an N-channel JFET.
Why UJT is called unijunction?
A Unijunction Transistor (UJT) is a three terminal semiconductor switching device. Since there is only one rectifying junction within the device, it is called a ‘Unijunction’ transistor.
Why is emitter base junction of a transistor thin?
The base of a transistor is lightly doped than the emitter and is made narrow so that virtually all the electrons injected from the emitter (in an npn transistor) diffuse right across the base to the collector junction without recombining with holes.
What do you mean by reverse active?
Just as saturation is the opposite of cutoff, reverse active mode is the opposite of active mode. A transistor in reverse active mode conducts, even amplifies, but current flows in the opposite direction, from emitter to collector.
Why is Collector wider than emitter and base?
The collector region is the largest of all regions because it must dissipate more heat than the emitter or base regions. It is designed to be large because in order to dissipate all the heater, the extra surface area allows it to do so.
What is the main function of unijunction transistor?
The Unijunction Transistor or UJT for short, is another solid state three terminal device that can be used in gate pulse, timing circuits and trigger generator applications to switch and control either thyristors and triac’s for AC power control type applications.