Inductors Definition

As one of the top electronic components distributors, JMChip Electronics offers a wide variety of inductors, coils, and chokes. JMChip carries several types of inductors, including toroid inductors, variable inductors, coupling inductors, foam inductors, combining inductors, choke inductors, TDK inductors, air core inductors, fixed inductors, Murata inductors, chip inductors, and more.

What are Inductors Electronic components?

Inductors, also known as chokes or coils, are a type of passive electrical component. They’re made from a simple wire coil that stores energy in the form of a magnetic field when an electric current flows through it. In electrical diagrams, the symbol for inductors is "L."

Like capacitors, electronic inductors are passive components, but they interact with magnetic fields and control magnetic flux. Inductors, also called coils, chokes, or reactors, are defined by their inductance—the ratio of voltage to the rate at which current changes. They’re commonly used in radio equipment to block AC while letting DC pass through.

A common example of an inductor you might use every day is the ferrite bead on your laptop's power cable, which helps reduce electrical noise. Inductors are usually made by winding a length of wire into a coil around a core material with high insulating properties. But inductors are more than just coils of wire with an insulator in the middle; they play a crucial role in many circuits.

How Do Inductors Work?

A simple magnetic field surrounds any wire with electricity flowing through it. The field gets stronger when you wind the wire into a coil. You can make the magnetic field even stronger by wrapping the wire around a magnetic core, like steel or iron.

This is how you create an electromagnet. The current affects the magnetic field around the inductors, so the field changes as the current fluctuates. When the magnetic field shifts, a voltage is produced between the inductors' terminals to counteract the change.

What Are Inductors Used For?

Discrete inductors aren’t very common in basic example circuits, so if you're just starting out, you probably won't see them much. But they’re quite common in power supplies. For instance, they’re used in making buck or boost converters and also in oscillators and filters in radio circuits.

On the other hand, you’ll come across electromagnets a lot more. They’re basically just inductors. You can find them in almost anything that uses electricity—like motors, relays, speakers, solenoids, and other electronic components. For example, a transformer is made up of two inductors wound around the same core.

Types of Inductors

Broadband Bias Inductors and Chokes - Most inductors don’t cover a wide enough impedance bandwidth for broadband bias applications. By connecting three or four inductors in series, you can improve bandwidth, but this also increases DC losses and filter complexity. A broadband bias choke, however, offers a large bandwidth in a single inductor package.

Multi-Layer Surface Mount Inductors - This type of coil has several layers of wire wrapped around an inductor, with insulation layers added to achieve a high inductance level. We also have inductor components for both EMI and RFI, and a variety of wireless charging coils. Wireless charging coils are used for DC-DC currents and inductive charging; any wireless charger relies on these inductive components.

Wire-Wound Surface Mount Inductors - These are typically a wire coil wrapped around a magnetic component.

Leaded Inductors - These come in two main categories and are used in both low and high voltage situations.

What are Chockers?

An inductor connected in series (in line) with a conductor, like a wire or circuit board trace, acts as a low-pass filter by blocking or limiting changes in current. Inductors are sometimes called "chokes" because they limit or choke off current changes. For example, a broadband (wideband) bias choke connected to an amplifier's DC bias blocks a wide range of high frequencies while letting the DC current pass through. This way, a bias choke separates the DC bias from the RF signal going to the amplifier.

Guide on Buying Electrical Inductors

Top 10 Electric Inductors Manufactures

The 10 most popular electronics inductor manufacturers you can find in the marketplace include Torex Semiconductor Ltd., TXC Corporation, Murata Electronics, Bourns, Wurth, TDK, and Vishay.

Frequently Asked Question

How are inductors attached to circuit boards?

Surface mount (SM) inductors are placed on top of a printed circuit board (PCB) on pads with solder paste and then reflow soldered. Through-hole (TH) inductors are mounted on top of the PCB with their leads fed through via holes in the board and then wave soldered on the backside.

In what applications are inductors used?

Inductors are mainly used in electrical power and electronic devices for these key purposes:

• Choking, blocking, attenuating, or filtering/smoothing high-frequency noise in electrical circuits
• Storing and transferring energy in power converters (dc-dc or ac-dc)
• Creating tuned oscillators or LC (inductor/capacitor) "tank" circuits
• Impedance matching

What is a choke?

A choke is an inductor placed in series with a conductor, like a wire or circuit board trace, to block or limit changes in current. It acts as a low-pass filter. Because it restricts changes in current, it’s also known as a "choke." For example, a broadband (wideband) bias choke in the DC bias line of an amplifier blocks a broad range of high frequencies but lets DC current pass through. This way, the bias choke separates the DC bias from the RF signal going to the amplifier.

The Federal Communications Commission (FCC) sets standards and certifies electronic devices sold or made in the United States to meet electromagnetic interference (EMI) requirements. Globally, standards organizations like CISPR, IEC, ISO, and EN handle electromagnetic compatibility (EMC) standards. FCC regulations are mandatory for devices such as computers, switched-mode power supplies, TV receivers, transmitters, and industrial, scientific, and medical (ISM) devices that emit RF radiation. Inductors are used in circuits to reduce EMI by attenuating high-frequency noise to comply with EMC emission and immunity standards.