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What are Transistors, their common types, and uses?

Transistors are common semiconductor devices found in numerous electronic assemblies, featuring three terminals that allow them to amplify or switch electronic signals and power. As a basic building block of modern electronics, transistors aid the operation of radios, calculators, computers, and other everyday devices that we rely on. Generally, transistors may be classified as either Bipolar Junction Transistors (BJT) or Field Effect Transistors (FET), each of which varies in its characteristics and functionality. To help you understand the use of transistors and their types, we will discuss them briefly.

The Bipolar Junction Transistor is the first type to be mass-produced, coming in the form of a two-junction diode combination that may be formed through placing a thin n-type semiconductor layer between two p-type semiconductors, or the reverse. In a p-n-p type BJT, two p-n junctions are present, creating a base-emitter junction and a base-collector junction.  Such BJTs are quite useful for amplifiers due to the fact that the currents located at the collector and emitter may both be controlled with a small base current. With an n-p-n transistor, the emitter-base junction is forward biased, and the base-collector junction is reverse biased. As electrons pass from the emitter to the collector, the emitter will send electrons to the base as determined by the base, and the collector will then send the electrons to the next section of the circuit.

FETs most commonly come in the form of metal-oxide-semiconductor field-effect transistors (MOSFET), featuring pins that are the gate, source, and drain. As such, they have operations that differ from BJTs to a degree. The block, or substrate, of the transistor is the base, and two sides are highly doped with an n-type impurity. With these regions, the drain terminals may both be established. The surface of the substrate features a coating of silicon dioxide, ensuring that the component has insulation. With the use of an insulated metallic plate that is placed on top of the insulating silicon dioxide layer, a capacitor plate may be formed. From this plate, the gate terminal is established. To finalize the DC circuit, a voltage source is connected between the two n-type regions of the component.

As discussed before, transistors often generally serve as switches or amplifiers. When acting as switches, transistors establish the binary on/off effect that allows for a circuit to be switched, all while being devoid of an actuator. Instead, voltages are used for switching as the transistor manages the flow of power between parts of a circuit. Switch-type transistors are commonly found within memory chips, millions being present for the means of switching on and off.

When acting as an amplifier, on the other hand, the transistor is capable of using small currents to create a much higher current at the output. Depending on the configuration of the transistor, it may be used to create current gain, voltage gain, or both. Generally, such amplifier transistor types find use in sound reproduction, radio transmission, and signal processing applications.

As transistors are a basic building block of modern electronics providing for voltage control, switching, and amplifying, it is important that one has reliable components for their system. ASAP Global Supplies is a website owned and operated by ASAP Semiconductor, and we are your sourcing solution for top quality transistor components and other electronic hardware that you require. As quality is the cornerstone of our operations, we ensure that all items are subject to visual inspections, testing, document verification, and other measures as necessary to guarantee their condition. We are also the only independent distributor with a strict NO CHINA SOURCING pledge, meaning that we choose to stock items from leading global manufacturers that we trust. Send us a completed RFQ form or give us a call or email at your earliest convenience and see how ASAP Global Supplies can serve as your strategic sourcing partner today.


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