– What is limiting computer processors to operate beyond the current range of clock frequencies (from 3 to up 5GHz)?
In: Engineering
A lot of great answers here on how timing and thermals limit CPU clock speeds. One of the main ways we have overcome these is by making the electronics smaller (smaller transistors). I’d like to add an interesting phenomenon called Quantum Tunneling, which is one of things that limits how small we can make electronics.
The simplified ELI5: imagine 2 wires carrying 2 signals (streams of electrons) right next to each other. In quantum mechanics there is a very small probability that an electron on one wire will spontaneously appear on the second wire. In almost every scenario this probability is so tiny (basically zero) that we can just ignore this effect. As you make the wires smaller and closer together down to the quantum level, the effect gets worse.
On a computer chip you have transistors that turn on and off. A transistor is basically a switch between 2 wires. When the transistor is “on” it connects both wires together and electrons can travel across, and when it is “off” it keeps the wires separate and blocks electrons from crossing. This is the basic building block of every computer. As transistors have gotten smaller and smaller, we’ve reached the point where even if the transistor is “off” we still have electrons jumping across the wires because of quantum tunneling.
Companies have come up with innovative solutions to workaround this by making the transistors into different shapes or using different materials to mitigate the effects of quantum tunneling. But as we are at 5nm transistors now, it is still one of the major factors preventing us from easily going smaller.
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