BJT DefinitionA Bipolar Junction Transistor (BJT) is defined as a three-terminal semiconductor device used for amplification and switching.Applications of Bipolar Junction TransistorThere are two types of applications of bipolar junction transistor, switching and amplification.Transistor as a SwitchIn switching applications, a transistor operates in either the saturation or cutoff region. In the cutoff region, the transistor acts as an open switch, while in saturation, it acts as a closed switch

BJT as a Switch DefinitionA BJT (bipolar junction transistor) is defined as a device that acts as a switch by controlling the base-emitter current to change the emitter-collector resistance.A switch creates an open circuit (infinite resistance) when in the ‘OFF’ position and a short circuit (zero resistance) when in the ‘ON’ position. Similarly, in a bipolar junction transistor, controlling the base-emitter current can make the emitter-collector resistance nearly infinite or nearly zero.In a tra

How Dose a Transistor Work?Transistor DefinitionA transistor is defined as a semiconductor device used to amplify or switch electronic signals.There are different types of transistors available, but we’ll focus on the NPN transistor in common emitter mode. This type has a heavily doped and wide emitter region, which contains many free electrons (majority carriers). The collector region is wide and moderately doped, so it has fewer free electrons than the emitter. The base region is very thin and

Bipolar Junction Transistor DefinitionA Bipolar Junction Transistor (BJT) is a three-terminal device. It can function as either an amplifier or a switch, requiring one input circuit and one output circuit. To handle this with only three terminals, one terminal serves as a common connection for both input and output. The choice of the common terminal depends on the application. There are three types of transistor connections: common base, common emitter, and common collector. Common Base Transist

What is a NPN Transistor?NPN Transistor DefinitionAn NPN transistor is a widely used type of bipolar junction transistor, where a P-type semiconductor layer is flanked by two N-type layers. Construction of NPN TransistorAs discussed above, the NPN transistor has two junctions and three terminals. The construction of the NPN transistor is as shown in the below figure. The emitter and collector layers are wider compared to the base. The emitter is heavily doped. Therefore, it can inject a large n

What is a PNP Transistor?PNP Transistor DefinitionA PNP transistor is defined as a bipolar junction transistor with an N-type semiconductor sandwiched between two P-type semiconductors. Symbol of PNP TransistorThe symbol includes an arrow on the Emitter showing the direction of conventional current flow. Current Flow DirectionIn a PNP transistor, the current flows from the Emitter to the Collector.Working PrincipleThe positive terminal of a voltage source (VEB) is connected with Emitter (P-type)

What is a Darlington Transistor?Darlington Transistor DefinitionA Darlington transistor is a semiconductor device that pairs two BJTs to achieve a very high current gain, functioning as a unified component.Darlington Transistor CircuitThe Darlington Transistor consists of two PNP transistors or NPN transistors connected back to back. It is a single package with a common collector terminal for both transistors.The Emitter terminal of the first transistor is connected with the base terminal of the

What is a PIN Diode?PIN Diode DefinitionA PIN diode is a specific type of diode that features an undoped intrinsic semiconductor layer of silicon or germanium between the heavily doped p-type semiconductor and n-type semiconductor layers. Unlike standard diodes, it includes this additional layer, which poorly conducts electric current but is essential for certain electronic applications. It’s like having a p region, followed by an intrinsic region and then an N region, thus making it a PIN diode

What is an Ideal Diode?Ideal Diode DefinitionAn ideal diode is defined as a perfect diode without any flaws, operating ideally in both forward and reverse biased conditions. Typically, a diode works in either forward or reverse bias. We can analyze the characteristics of an ideal diode in these two modes separately.Characteristics of Ideal Diode when Forward Biased Zero ResistanceIn forward bias, an ideal diode offers zero resistance to current flow, making it a perfect conductor. This means the

What is Diode Current Equation?Diode Current Equation DefinitionThe diode current equation expresses the relationship between the current flowing through the diode as a function of the voltage applied across it. Mathematically the diode current equation can be expressed as: I is the current flowing through the diodeI0 is the dark saturation current,q is the charge on the electron,V is the voltage applied across the diode,η is the (exponential) ideality factor.is the Boltzmann constantT is the ab