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What is a CPU Transistor?

Allan Robinson
Allan Robinson

A transistor is a semiconducting device that switches and amplifies electronic signals. It has a minimum of three terminals that connect it to an electronic circuit. The transistor was invented during the early 1950s, and it quickly replaced vacuum tubes in electronic devices. These devices are now an essential component of almost all electronic devices, such as the central processing unit (CPU) of a computer. A CPU transistor is typically part of an integrated circuit although it can also be purchased individually as well.

The terminals in a CPU transistor have specific names depending on the type of transistor. The terminals of a simple bipolar transistor are called the collector, emitter and base. The current or voltage that’s applied to the base affects the current flow from the collector to the emitter.

A Central Processing Unit (CPU).
A Central Processing Unit (CPU).

The voltage at the base of the transistor can be used to turn on and off the current flow from the collector to the emitter. This type of transistor is a switch and is a common type of CPU transistor called a logic gate. A switch generally does not allow current to flow through it unless the voltage at the base is above a minimum threshold. The voltage at the base is controlled by other components in the circuit.


A CPU transistor can also be an amplifier. This type of transistor uses the voltage at the base to control the amount of the current that flows through the amplifier. This means that a small change in the voltage at the base can produce a large difference in the voltage between the collector and emitter.

Transistors provide significant advantages over vacuum tubes in computers. A CPU transistor is much smaller than its vacuum tube equivalent, allowing for the miniaturization of computers. The manufacture of transistors can be automated to a greater extent than that of vacuum tubes, which means that transistors are cheaper than vacuum tubes.

CPU transistors are an important component of computers.
CPU transistors are an important component of computers.

The first patent for a transistor was filed by Julius Edgar Lilienfeld in 1925 although he did not actually construct such a device. Herbert Matare discovered semiconductor effects while working on a Doppler radar system in 1942. Then technology progressed, and in 1947 while working at AT&T's Bell Labs, Walter Brattain and John Bardeen discovered that a germanium crystal could amplify an electrical current. Gordon Teal built the first silicon transistor for Texas Instruments in 1954, and the CPU transistor, which is a metal oxide semiconductor (MOS) transistor, was first built at Bell Labs in 1960.

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Discussion Comments


@miriam98 - I, for one, am glad for the invention of the CPU transistor. It’s what makes computer architecture possible, not only for desktops, but for laptops as well.

Can you imagine a computer built out of vacuum tubes? Well believe it or not, that’s what the early computers back in the 1940s and 1950s were.

They had the ENIAC computer which filled a room with vacuum tubes but it was only a fraction as powerful as a modern day calculator. You definitely didn’t have “laptops” back then.


@SkyWhisperer - Yeah, I think whether you are talking about an AMD processor or a Pentium 4 processor, you are talking about packing more and more transistors into that little chip.

That’s really what makes the processors more powerful. You are just adding more switches so to speak, and as a result, the chip can do more. It becomes even more impressive when you look at quad core where you have four chips doing the work.

Once we get into nanotechnology, we’ll have zillions of little transistors. Maybe the nanocomputer will do astronomical things, like solve for Einstein’s unified field theory or something like that.


A CPU transistor is what makes a computer possible. Basic processor design reveals that at its core, a computer is nothing more than a bunch of switches.

I took a course once where we learned about binary numbers. We learned about this basic numbering system, which was all 1’s and 0’s. With these 1’s and 0’s it’s possible to represent just about any number imaginable, and of course the 1’s and 0’s can act as on and off gates too.

Since the transistor can act as a switch, it’s on or off state can correspond to a 1 or 0 respectively. This is what all computers are at their core. Needless to say there may be millions of transistors in a CPU chip, making all of this possible, thanks to the miracle of miniaturization. Stuff keeps getting smaller and more powerful too, and I think there is no end in sight to this trend really.

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      A Central Processing Unit (CPU).
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