Transistor — A simplified explanation

Understand the innovation that shaped the modern world

You are reading this article on a mobile or laptop and guess what, they have millions and billions of transistors.

So my rule of thumb is “If you are surrounded by something in daily life you should have understanding why its there and what it does”

So today let's explore what a transistor is in very easy terms, we won’t go into its internal working and all. (As if saying this would magically make you want to read the whole article 😉)

Switch

Before jumping on the transistor let's understand the switch, it's the basic one present around you.

Here you can see a physical switch, there is a cell connected with wires and a bulb and when the switch is closed (connected) the bulb glows 💡 which let's say is ON state and when the switch is open (disconnected) then the bulb will not work, being in OFF state.

The switch helps to gain control on these, ON and OFF states, simple as that.

Why should we care about the switch?

Binary

We are learning transistors but talking about the switch to turn the on and off bulb, why?

For our ease let's say ON → 1 and OFF → 0

These 0 and 1 are the binary digits, and the entire computer working is dependent on the binary.

Computer understands nothing but binary.

• You captured a great photo of yourself in front of the mountain and posted it on your very favorite social media platform. For humans, it's a mountain and sky and colors, etc but for computers, it is a collection of 1’s and 0’s, the same thing with music and all. (All of your good shots, and music are nothing but a collection of 0’s and 1’s 😯)
• Take anything you doing on a computer, it's all a collection of 1’s and 0’s and operations on those.

Binary Operation

If you use any computer or smart device you are majorly doing binary operations and making those switches 1 and 0 at a rapid speed over a huge circuit.

Modern computer does millions and billions of operations per second.

Operations include copying the value from one location of memory to another, doing some arithmetic and logic operations, etc.

Let's take the example of the previously taken photo, when you open that photo and try to edit it, let's see what happens:

Load to RAM

When you try to open a photo it will be loaded to RAM, and like I said earlier, it will be in the collection of 0’s and 1’s and collectively the computer can understand what the photo is.

The image above is a very basic representation of the actual image (modern images have multiple layers and a multi-dimension matrix of those numbers) but you got the gist.

Now let's relate the image to the switch. Each bit of the photo’s binary data corresponds to the state of a switch in RAM. A ‘0’ might represent a switch that’s off, and a ‘1’ might represent a switch that’s on.

So, a sequence of switches in the state of ONand OFFin a specific order represents the binary data of your photo.

And we can slide the photo to another quickly, now computers have a hard time making those switches toggle again and again to show that specific image for you.

Edit photo

Now you had the urge to bump the saturation or brightness or whatever, behind the scenes, it's some arithmetic operation going on (based on the filter you apply it can be a simple to complex operation).

Increasing brightness might involve adding a fixed value to the color component of each pixel. In the above image there are 48 pixels and doing some edits means some arithmetic operation is performed 48 times, imagine it on the modern image, it can easily have millions of pixels.

Doing such arithmetic operations is the basic task of a computer, it involves connections and communications of many basic logic gates to achieve them.

For eg:

The XOR and AND gates shown above is the result of a smart combination of switches for eg:

Switches are arranged in such a manner that if it is OFFin any input then the result on output is always OFF.

When applying our image filter the pixel values go through similar switches millions of times, can you imagine it with a mechanical switch that has a physical ON OFF button?

Limitations of Mechanical Switches

I think I was able to convince you that modern computing operations are all based on binary principles and require some form of switching to perform their tasks.

So, it’s crucial to understand that conventional mechanical switches are not capable of handling the immense volume of operations required by modern computing devices.

Speed

Mechanical switches, due to their physical nature, operate relatively slowly. They must physically move between positions to open or close a circuit, which takes a significant amount of time. Modern computers, however, operate at speeds measured in gigahertz. At such speeds, the delay introduced by mechanical movement will cause the entire system to be slow.

Size

Additionally, the size of mechanical switches limits how many can be packed into a small space. Modern smart devices can adjust in our palms so it's important to consider the size of the switch.

Introducing Transistors

Till this point, we understood that binary and binary operation is the base for computers and it involves some sort of switching logic, and physical switch is a bottleneck to modern computers due to speed and size.

With this base knowledge, we are in the best spot to understand transistors.

The transistor emerged as a revolutionary solution to the limitations of physical switches. They are tiny, efficient, and incredibly fast. It operates through the manipulation of electric currents.

It consists of three layers: the emitter, the base, and the collector. By controlling the flow of electrons between these layers, transistors can be used to act as electronic switches.

In 1 second, a transistor can potentially switch on and off millions to billions of times. So no wonder it is a revolutionaly invention.

The transistor is made up of a semi-conductor so we can control its behavior by adding impurities (doping) and with a small current we can control and act it as a switch or logic gates etc.

So, this is about transistors without going into inner details.

Fun Facts

1. Moore’s Law

Gordon Moore, co-founder of Intel Corporation noticed a trend in the semiconductor industry that the number of transistors on a microchip was doubling approximately every two years, leading to a consistent increase in computing power and a decrease in cost per transistor.

There are some limitations to this law and an active debate that this law is dead already.

2. Nobel Prize

The transistor was invented by John Bardeen, Walter Brattain, and William Shockley and they were awarded the Nobel Prize in Physics.

3. Nanotech

Research is going on to produce a 1nm transistor, but there is already a 5nm - 3nm transistor. Even if we consider a 5nm transistor, you could line up 100,000 of these 5nm transistors to span the length of just one single grain of table salt.

4. Growth

The Intel 4004, released in 1971 contained 2,300 transistors, and today's latest chip can easily contain 10–15 billion transistors.

The invention of the transistor has shaped the modern world and the rapid growth of the nanotech and going down to the atomic level is out of imagination for normal people. So let's take time to appreciate those great people and inventions like these.

Thank you for teaching to this point, don’t forget to clap 👏 and follow for more simplified content in Computer Science.