# Eli5 How do integrated circuits work?

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Eli5 How do integrated circuits work?

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The basic concept is ultra small silicon chip with tiny field effect transistors. The magic of an integrated circuit is the transistors. There’s a long discussion about what those are, how they work, and how we manufacture them. But think of it as a gate. You can organize them in clever ways by linking their inputs and outputs in such a manner that they perform a handful of simple functions. When you put billions of them together you can combine lots of simple functions into higher level complicated functions and now you have the basis for the complexity of most modern computing.

There’s a statue of the guy that patented it outside the building he worked in when integrated circuits were invented. It’s still Texas Instruments property but it’s operated by a defense contractor right now on a lease. They’ve taken that integrated circuit design and advanced it enormously to create circuitry components that are the basis of advanced radar and communications equipment.

Thorough a complex series of what are called ‘gates’. A gate reacts to electrical signals, and open or close according to their design. When the gate is open, signal is allowed to pass through.

A simple example is an AND gate. This type of gate takes two signal inputs and a voltage input, then sends that input as output if both gates are in the same position. Other gates include OR, XOR, NOT, and so on. A circuit can be built with a combination of gates, and through clever crafting can be designed in a manner that performs mathematical operations.

Same way normal circuits work

An IC is just a nice compact package that you can place. It could contain just two transistors, or an opamp made of a hundred, or a crystal with supporting parts, or billions of transistors in a processor or memory module

Medium scale integration parts like OpAmps are nice because they clean up a design. You could hand build an OpAmp from discrete parts but you’d have dozens of transistors, resistors, and capacitors sprinkled around. None would need to be very big to do their job but they end up large so you can handle them. By putting them all together inside a little plastic housing you can put down just a single part for a complex function instead of having to build it all by hand each time

Large scale and very large scale integration parts(memory units and processors) are impractical to make by hand so an Integrated circuit is a necessity

If you really want to know, Ben Eater has a YouTube channel with a playlist for his “Breadboard Computer”. It will take you the whole way from explaining a PN Junction all the way to a basic programming language for a very simple CPU.

The series requires a bit of concentration, but anyone can follow along, and at the end you’ll know exactly what happens inside a microprocessor – what people commonly think of as an IC. Even if you’re thinking of other IC’s like memory chips, etc., it’ll give you a massive start to completely understanding deeper than most degree-level students will. Amazing course.