device is often called the bipolar junction transistor because its operation requires that the negatively charged electrons and their positively charged counterparts (the holes corresponding to an absence of electrons in the crystal lattice) coexist briefly in the presence of one another.
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What do you mean by junction transistor?

junction transistor – a semiconductor device capable of amplification. electronic transistor, transistor. base – (electronics) the part of a transistor that separates the emitter from the collector. collector – the electrode in a transistor through which a primary flow of carriers leaves the region between the …

Why a bipolar junction transistor is called so name its terminals?

Whereas a field-effect transistor is a unipolar device, a bipolar transistor is so named because its operation involves two kinds of charge carriers, holes and electrons. … Therefore, if the emitter and collector terminals are reversed, a bipolar transistor has a much lower hFE and does not function as intended.

Why BJT is called as bipolar transistor?

Simply put, a BJT is a three-terminal semiconductor device. The name “bipolar” comes from the fact that this type of transistor contains two types of semiconductor material—one positive type (p-type) and one negative type (n-type)—through which a current flows. Bipolar junction transistors usually contain silicon.

What is a junction transistor What are its two types?

Transistors are basically classified into two types. They are: Bipolar Junction Transistors (BJT) and Field Effect Transistors (FET). The BJTs are again classified into NPN and PNP transistors. The FET transistors are classified into JFET and MOSFET.

How is a junction transistor formed?

The Transistor is a three terminal solid state device which is formed by connecting two diodes back to back. Hence it has got two PN junctions. Three terminals are drawn out of the three semiconductor materials present in it. … The three terminals drawn from the transistor indicate Emitter, Base and Collector terminals.

What is the main function of junction transistor?

A junction transistor is a semiconductor triode capable of producing amplification.

Why Ujt is called Unijunction?

The UJT consists of an n-type silicon semiconductor bar with an electrical on each end. … Since the device has three terminals and one pn-junction, for this region this is called as a Unijunction Transistor (UJT).

How does a bipolar junction transistor work?

How does BJT Work? For an NPN transistor, it consists of a layer of P-doped semiconductor between two layers of N-doped material, where electrons are passed from the emitter to the collector instead. The emitter then “emits” electrons into the base, with the base controlling the no. of electrons the emitter emits.

What is a bipolar junction transistor used for?

Bipolar transistors are still used for amplification of signals, switching, and in digital circuits. Specialized types are used for high voltage switches, for radio-frequency amplifiers, or for switching heavy currents.

Why are transistors referred to as unipolar and bipolar semiconductors?

BJT is called bipolar because the current in a BJT flows due to both electron and hole carriers, whereas the current in a Field Effect Transistor (FET) flows due to either electron carriers for N-type FET or hole carriers for P-type FET, hence they’re called unipolar transistors.

Which is an example of bipolar junction transistor?

The two types of bipolar transistors are the PNP Transistor, whose three regions are p type, n type, and p type respectfully, and NPN Transistor, whose regions are n type, p type, and n type respectfully.

Why FET is called voltage control device?

FET is a voltage-driven/controlled device, i.e. the output current is controlled by the electric field applied. The current through the two terminals is controlled by a voltage at the third terminal (gate). It has a high input impedance. So, a FET is a voltage-controlled current source.

What is junction transistor mention its types How are they represented?

These regions form two p-n junctionsbetween them. Depending on thenumber of n and p-typesemiconductors in the transistor, they are of two types: n-p-n transistor: A p-type semiconductor (base) separatestwo segments of the n-typesemiconductor (emitter and collector).

How are transistors named?

Bipolar junction transistors are the most commonly used type. To help identify them, transistors are labeled with number and letters on their casings. Transistors are labeled according to the numbering system that is used. … An ordinary bipolar transistor has three leads, so the first digit for it will be 2.

What is the left hand section of a junction transistor called?

d) depletion region. Explanation: The main function of this section is to supply majority charge carriers to the base. Hence it is more heavily doped in comparison to other regions. This forms the left hand section of the transistor.

When was junction type transistor is invented?

The first bipolar junction transistors were invented by Bell Labs’ William Shockley, which applied for patent (2,569,347) on June 26, 1948. On April 12, 1950, Bell Labs chemists Gordon Teal and Morgan Sparks had successfully produced a working bipolar NPN junction amplifying germanium transistor.

What are the types of junction transistor?

  • NPN transistor.
  • PNP transistor.
How many junction are there in diode?

How many junction/s do a diode consist? Explanation: Diode is a one junction semiconductor device which has one cathode and anode.

Why UJT is called relaxation oscillator?

The UJT relaxation oscillator is called so because the timing interval is set up by the charging of a capacitor and the timing interval is ceased by the rapid discharge of the same capacitor.

How many pn junction are there in UJT?

UJTBJTOnly one junction is present in UJT.It consists of two Junctions. It is a two junction transistor.

Why FET is called unipolar?

FETs are also known as unipolar transistors since they involve single-carrier-type operation. That is, FETs use either electrons or holes as charge carriers in their operation, but not both. … The most widely used field-effect transistor is the MOSFET (metal-oxide-semiconductor field-effect transistor).

What is difference between PNP and NPN?

An NPN transistor has a piece of P-type silicon (the base) sandwiched between two pieces of N-type (the collector and emitter). In a PNP transistor, the type of the layers are reversed. … NPN and PNP transistors have very similar schematic symbols. The only difference is the direction of the arrow on the emitter.

What is Alpha Beta and Gamma in transistor?

The Common Emitter Amplifier Circuit A transistors current gain is given the Greek symbol of Beta, ( β ). As the emitter current for a common emitter configuration is defined as Ie = Ic + Ib, the ratio of Ic/Ie is called Alpha, given the Greek symbol of α.

When a transistor is used as a switch?

One of the most common uses for transistors in an electronic circuit is as simple switches. In short, a transistor conducts current across the collector-emitter path only when a voltage is applied to the base. When no base voltage is present, the switch is off. When base voltage is present, the switch is on.

Is pn junction a bipolar or unipolar?

PN junction diode is bipolar as conduction is due to both holes and electrons. Schottky diode is unipolar as conduction is only due to only one carrier.

What bipolar means?

Bipolar disorder (formerly called manic-depressive illness or manic depression) is a mental disorder that causes unusual shifts in mood, energy, activity levels, concentration, and the ability to carry out day-to-day tasks. There are three types of bipolar disorder.

Which junction is forward biased when transistor is used as an amplifier?

A. Emitter-base junctions must be reverse biased, and a collector-base junction must be forward biased.

Why transistor is considered as current operated device?

Re: Transistor A bipolar transistor is said to be current controlled because when it is biased in the active region the output (collector) current is controlled from the input (base) current.

What is the difference between BJT and FET transistors?

BJTs and FETs are two different kinds of transistors and also known as active semiconductor devices. … The major difference between BJT and FET is that in a field-effect transistor only majority charge carries flows, whereas in BJT both majority and minority charge carriers flow.