how is a transistor such a fast switch


Our CPUs have billions of transistors and each of those transistors operates at billions of operations per second (GHz)I understand how transistor is a switch and how we combine them to form logic gates

but cant comprehend how it switches on and off so fast

P.S. not so sure if this is a technology , physics or engineering question 😅

In: 2

They switch so fast because they are so incredibly small.

The transistors a computer uses are MOSFET types. They work by attracting electrons to build bridges between conductive islands. How fast you can assemble that bridge is equal to how fast you can accumulate a charge on the opposite side of the insulator that is used to attract it. This is called the “gate capacity” (you’re literally charging a tiny capacitor).

A capacity is charged following a curve that depends on it’s capacity times resistance. Both of these get smaller the smaller the geometry is, and for the nanometer sized ones in a computer this ends up being on the scale of fractions of nanoseconds too.

Compare it to filling a bucket, but the bucket is very tiny, and the hose you use is very short.