Tag: Electronics
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Principle of Operation and Applications of a Laser Diode
Laser diodes are PN junction devices under a forward bias. LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser Diode Structure The laser diode structure can be divided into two categories: An example of an edge-emitting laser diode structure is shown in Figure 1.0 below. This type of structure is termed…
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How the Photoelectric Effect Influences Semiconductors
A photoelectric effect is any effect in which light energy is converted to electricity. When light strikes certain light-sensitive materials, it may cause them to give electrons or change their ability to conduct electricity or may cause them to develop an electrical potential or voltage across two surfaces. When a surface is exposed to electromagnetic…
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The Varactor Diode
The varactor also termed to as varicap, is a diode that behaves like a variable capacitor, with the PN junction working like the dielectric and plates of a common capacitor. Because of this, the symbol of the varactor is as shown below: A varactor diode employs a PN junction in reverse bias and has a…
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Power MOSFET Motor Control
Because of the very high input gate resistance of MOSFETs, MOSFET’s fast switching speeds, and the ease at which they can be driven makes them ideal to interface with op-amps or standard logic gates. Nevertheless, care must be taken to ensure that the gate-source input voltage is correctly chosen because when using the MOSFET as…
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Metal Oxide Semiconductor FET (MOSFET)
The Metal oxide semiconductor FET (MOSFET) also known as the insulated-gate FET (IGFET) is similar to JFET but exhibits even larger resistive input impedance due to the thin layer of silicon dioxide that is used to insulate the gate from the semiconductor channel. This insulating layer forms a capacitive coupling between the gate and the…
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The Junction Field Effect Transistors (JFET)
The bipolar transistor has several disadvantages: it has low input impedance because of forward biased emitter junction, it has small high-frequency gain, it has considerable noise level and it is non-linear when |VCE| < 2V. Although low input impedance problem may be improved by careful design and use or more than one transistor, even so…
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Bipolar Junction Transistors (BJT)
By placing two PN junctions together we can create a bipolar junction transistor. In a PNP transistor the majority charger carriers are holes and typically germanium is favored for these devices. In NPN transistors the majority charger carriers are electrons; for this case, silicon is typically used. The thin and lightly doped central region is…
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Multiplexers and Demultiplexers in Digital Circuits
Multiplexers and demultiplexers are devices that route signals. A multiplexer also called a data selector takes one of several inputs and connects it to a single output. The input line that is connected is determined by the binary applied to the address lines. The diagram below shows a multiplexer with four input lines: The two…
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Tuned Amplifier Applications
A tuned amplifier operates over a band of frequencies centered on a resonant frequency. Its two main requirements are to provide high gain and good selectivity. We have several applications in telecommunications systems where it is necessary to amplify a narrow band of frequencies centred on one frequency. A typical example is shown in the…
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The Different Applications of Diodes
Diodes are used in many applications for example diodes are employed in reverse-polarity protection, used in voltage regulators, etc. We discuss these applications plus more in this article. Here are some of the different applications of diodes: Transient Suppression with Fly-back diodes Transient Protection When current flowing through an inductor is suddenly switched off, the…