What is a transistor?
A transistor is a tiny switch that a voltage turns on or off. Billions of them work together in a big chip to compute and store data.
1. A tap for electricity
A transistor works like a water tap, and its gate is the handle. Instead of a hand, a voltage sets it: about 1 volt (V) opens it, and 0 V closes it.
2. Switches build logic gates
A few transistors make a logic gate, a tiny decision maker: a NOT gate turns on into off, and off into on. Many gates together add numbers, store data and build a whole processor.
3. Each flip costs energy
Each flip fills or empties a tiny store of charge, like a bucket of water. Filling it takes energy, so every flip costs a little.
4. A closed tap still drips
Even when it is off, a transistor leaks a little current, like a dripping tap. Billions of small leaks add up.
5. Smaller fits more
Smaller transistors fit more on each chip, and they switch faster with less energy per flip. So each new generation makes them smaller, though tiny transistors can leak more.
Words to know
- Transistor
- A tiny switch in a chip. A voltage turns it on or off.
- Gate
- The part of a transistor that turns it on or off, like a tap's handle.
- Current
- Electricity moving along a wire, like water in a pipe.
- Voltage
- The push that moves electricity. Chip parts use about 1 volt (V).
- Logic gate
- A few transistors that make a tiny decision, such as NOT. It is not the same as a transistor's gate.
- Charge
- Electricity stored in a tiny space, ready to flow.
- Leakage
- Current that slips through a switch that is off.
Where you meet it at work
Chips have built-in ways to save power, and each one cuts one of two costs: the energy of each flip, or leakage. Knowing them tells you why the team tests what it tests.
Check yourself
Why does a chip use some power even when its switches are off?Think first, then tap to see the answer.
Off switches still leak a little current.