Our whole life whirls around Electronics. Our phones, laptops, Computing systems, television, washing machine, control boards and this list goes on endlessly. These micro devices which are so handy for us, used to be mammoth sized decades ago, prior to the revolution of Microelectronics.
Early systems incorporated Vacuum tubes, amplifying that operated with the flow of electrons between plates in a vacuum chamber.
The first transistor invented in 1940s replaced the vacuum tubes. they exhibited infinite lifetime and occupied much smaller volume than vacuum tubes.
With the advent of Microelectronics in 1960s, many transistors began to be integrated on one chip. As the complexity of ICs increased, so did their technology was used in more and more devices.
Now, what were these devices that made our work so easy? How are they different and how are they same? What purpose do they fulfill, we shall know now.
* Diode. Ever thought of a simple mobile phone charger? A charger converts AC voltage at 220 V and 50 Hz to a DC of 3.5 v. The voltage is first stepped down by a transformer and then AC is converted into DC. We need a device that knows the discrimination between positive and negative voltages, passing only one and blocking other. This device is called Diode, a two terminal device. You can read about it in any standard book.

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* Bipolar Transistor. This is a three terminal device. It switches and amplifies electronic signals and electronic power. It can act as a voltage dependent current source. A diode has one p—n junction whilst a transistor has two p—n junctions. An electronics engineer needs to read about its structure, operation, large—signal and small—signal models.

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* MOS transistors or MOSFETS. It stands for Metallic Oxide Semiconductor Field Effect Transistor. It consists of a conductive plate atop a semiconductor substrate and two junctions called source and drain in the substrate. The MOS technology has culminated billions of transistors on a single chip and sophisticated signal processing circuits.

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* CMOS technology. MOS devices are of two types PMOS and NMOS. What if we build both of them on the same wafer? A Complementary MOS (CMOS) devices are now dominant in spite of the higher cost. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits.

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* BiCMOS. This dominant technology combines the Bipolar and CMOS technologies for high speed, low power and highly functional VLSI circuits. Generally this means that high current circuits use metal–oxide–semiconductor field-effect transistor (MOSFETs) for efficient control, and portions of specialized very high performance circuits use bipolar devices.

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Images:
1. sparksfun.com (http://learn.sparksfun.com)
2. http://create—and—make.com (http://create—and—make.com)
3. Electronic Circuits and Diagram-Electronics Projects and Design (http://circuitstoday.com)
4. Wikimedia Commons (http://commons.wikimedia.org)
5. Electronic Products Magazine – Component and Technology News – Electronic Products (http://electronicproducts.com)
Source:
Fundamentals of Microelectronics by Behzad Razavi. WILEY.
Wikipedia (http://Wikipedia.org)