A transistor is a device used to regulate the flow of electrical signals. The basic role of transistors is to control or amplify electrical signals, which makes them an essential component of nearly every modern electronic device.

Who Invented the Transistor?

The transistor was developed at Bell Labs by John Bardeen, Walter Brattain, and William Shockley, and Bardeen and Brattain constructed the first functional transistor in 1947. The trio’s work revolutionized electronics and earned them the Nobel Prize in Physics in 1956.

Before transistors, devices like vacuum tubes were used to amplify electrical signals, but they were large, power-hungry, and prone to failure. Transistors solved these issues by being more reliable, smaller, and energy-efficient.

What Do Transistors Do?

Transistors are made from semiconductor materials like silicon, which can act as a conductor or an insulator depending on changes in the electrical current applied.

Functions

Switching: A transistor can act as a switch, controlling whether current flows through a circuit. In digital electronics, transistors switch between on (1) and off (0) states, allowing them to represent binary data. This simple mechanism is the foundation of all digital processing. A computer’s processor uses billions of transistors, turning on and off in rapid succession to process data and execute instructions.

Amplification: Transistors also can accept weak electrical signals and strengthen their output, which is especially important in analog electronics. For example, in audio devices, a small input signal can be amplified to drive speakers, enhancing the volume without distorting the sound. This ability to boost signals is why transistors are integral to devices ranging from hearing aids to televisions.

Learn More: Essential Electronic Components

How Do Transistors Work?

Transistors operate using three terminals: the emitter, collector, and base. The base acts like a gate that controls the flow of current between the collector and emitter. When a small current is applied to the base, it allows a much larger current to flow from the collector to the emitter, amplifying the input signal in the process. While all transistors perform similar functions, there are various types depending on the specific needs of a circuit.

Resistor Types

Bipolar Junction Transistor (BJT): This type of transistor has two junctions between different kinds of semiconductor material. It operates by injecting electrons and holes between the base and the collector/emitter terminals. There are also two polarities of BJTs. In NPN transistors, the current flows from the collector to the emitter when a positive voltage is applied to the base. In PNP transistors, the opposite occurs, and a negative voltage at the base allows current to flow.

Field-Effect Transistor (FET): This type of transistor uses an electric field to control the flow of current. The most widely used type of FET is the Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), which is widely used in microprocessors and digital circuits because they are more power efficient. MOSFETs come in two flavors: N-channel and P-channel, and they rely on positive or negative voltage applied to the gate (analogous to the base in BJTs) to control current flow.

Why Transistors Are So Important

Transistors are the foundation of modern computing because they are the key component in logic gates, which are, in turn, the building blocks of integrated circuits (ICs). Integrated circuits are found in virtually all modern electronics. ICs pack millions or billions of transistors onto a small chip, and these chips can perform complex tasks, from basic arithmetic to advanced computations that power artificial intelligence. The more transistors on a chip, the more processing power that chip has.

The ability to fit more transistors on a chip directly determines its processing power. Smaller transistors mean more can be packed into the same space, resulting in faster, more efficient chips.

The Role of Moore’s Law

The steady reduction in transistor size over the past decades has fueled Moore’s Law, the observation that the number of transistors on a chip doubles approximately every two years. This trend has led to exponential improvements in computing power, enabling the evolution from room-sized computers to smartphones and cloud computing systems.

While sustaining this pace is becoming challenging due to physical and economic constraints, the principles of Moore’s Law continue to drive innovation in chip design and new computing architectures, ensuring that performance continues to improve.

Learn More: What is Moore's Law

Every modern processor contains billions of transistors working in unison to handle calculations and manage data flow. Without transistors, we wouldn’t have computers, smartphones, or the internet. Beyond digital electronics, transistors are also essential for high-power systems, such as solar panels, wind turbines, and electric vehicles, because they efficiently control electrical power flows.

The Impact of Transistors

Transistors power nearly every modern electronic device and are critical to the development of more efficient and powerful computing systems. At Microchip USA, we do more than supply transistors; we are a full-line supplier capable of sourcing transistors, semiconductors, passives, connectors, and any electronic component your project requires. Serving industries ranging from medical and industrial automation to telecommunications and aerospace, our procurement specialists leverage a global network of trusted suppliers to help you secure the parts you need at competitive prices. Contact us today to discuss your component requirements. Contact us today!