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Author: Admin | 2025-04-28
Do it the same way. Like a junction transistor, a FET(field effect transistor) has three different terminals—but theyhave the names source (analogous to the emitter), drain(analogous to thecollector), and gate (analogous to the base). In a FET, thelayers ofn-type and p-type silicon are arranged in a slightly different way andcoated with layers of metal and oxide. That gives us a device called aMOSFET (Metal Oxide Semiconductor FieldEffect Transistor). Although there are extra electrons in the n-type source and drain,they cannot flow from one to the other because of the holes inthe p-type gate in between them. However, if we attach a positivevoltage to the gate, an electric field is created there that allowselectrons to flow in a thin channel from the source to the drain. This"field effect" allows a current to flow and switches the transistor on:For the sake of completeness, we could note that a MOSFET is a unipolartransistor because only one kind ("polarity")of electric charge is involved in making it work.How do transistors work in calculators and computers?In practice, you don't need to know any of this stuff aboutelectrons and holes unless you're goingto design computer chips for a living! All you need to know is that atransistor works like an amplifier or a switch, using a small currentto switch on a larger one. But there's one other thing worth knowing:how does all this help computers storeinformation and make decisions?We can put a few transistor switches together to make somethingcalled a logic gate, which compares severalinput currents and
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