What Is a Coupled Inductor?

What Is a Coupled Inductor?

If you’re wondering what a coupled inductor is, you’re not alone. This type of inductor is actually quite complex, and even engineers can have trouble understanding how they work. In this blog post, we’ll try to explain how coupled inductors work in simple terms. Hopefully by the end you’ll have a better understanding of this key component in electrical circuits.

What Is A Coupled Inductor?

A coupled inductor is an electronic component consisting of two or more inductors that are magnetically linked together. It has the ability to transfer energy in the form of an electromagnetic field between its coil windings. Coupled inductors can be used for various applications, such as coupling signals between circuits, providing impedance matching and creating transformers.

The main purpose of a coupled inductor is to provide magnetic coupling between two coils by connecting them with a common core material which allows them to share the same magnetic flux lines. This helps in reducing noise and improving signal integrity while transferring energy from one coil winding to another. Moreover, they can also be used as voltage regulators which allow current flow in both directions through different paths.

What Is A Coupled Inductor?

There are various types of coupled inductors such as single-layer, multi-layer and axial types. The single layer type consists of two inductors that are wound around the same core material while in case of a multilayer type, multiple inductors are wound around different layers to increase the number of turns. Axial inductors feature an additional winding which increases the total number of turns available for the device.

Coupled inductors can be used in various electronic circuits including amplifiers, radios, power supplies and other audio applications. They offer several advantages compared to other components such as low cost and high reliability. Furthermore, they also provide excellent performance in terms of efficiency and noise reduction making them ideal for use in diverse applications. [1]

What Are Common Applications For Coupled Inductors?

Coupled inductors are essential components in a wide range of solutions, from everyday power delivery to intricate electronic circuitry. Coupled inductors have an array of common applications, including:

  • Power transfer – Coupled inductors are commonly used in AC-DC and DC-AC converters, allowing for efficient power transfer between the two systems.
  • High frequency electronics – Coupled inductors can be found in high frequency electronic circuits like RF amplifiers and oscillators, where their ability to store energy is particularly useful.
  • Filtering – Coupled inductors can be used as low pass filters, removing undesired frequencies while preserving desired ones. This makes them ideal components for signal conditioning and noise reduction tasks.
  • Motor control – Coupled inductors are often used in motor control circuitry, where their high inductance and low reactance help to reduce the current ripple that is produced when a motor changes speed.
  • Telecommunications – Coupled inductors are used in telecommunications systems to couple different sections of an antenna or radio frequency circuit together. This helps with signal transmission and reception.

Coupled inductors can be highly beneficial components in many applications due to their ability to store energy and transfer it efficiently between circuits. With their versatility and wide range of uses, coupled inductors are essential components in many electronic devices.

These diverse applications make coupled inductors a valuable component in modern electronics and communications systems. By understanding their properties and the wide array of uses for them, engineers can use coupled inductors to construct efficient and powerful devices. [2]

What Are Common Applications For Coupled Inductors?

What Is The Difference Between A Coupled Inductor And A Transformer?

Coupled inductors and transformers are both devices that use electromagnetic induction to transfer electrical energy between two or more coils.

However, there are some key differences between the two.

The primary difference lies in how each device is used. A transformer is designed to change a voltage level, while a coupled inductor is usually used as an AC filter or noise suppressor — it doesn’t really affect the voltage levels at all. Coupled inductors can also be used to store energy, while transformers cannot. The physical construction of these devices also differs significantly; transformers have multiple windings around one core, while coupled inductors have multiple cores and no windings.

Coupled inductors and transformers both have their own unique applications and benefits, so it’s important to know the difference between them when selecting a component for an electrical circuit. While transformers are better suited for voltage conversion applications, coupled inductors are better at suppressing noise or storing energy. With this knowledge in hand, designers can choose the right component for their specific application.

What Is The Difference Between A Coupled Inductor And A Transformer?

How Do I Choose A Coupled Inductor?

Choosing a coupled inductor can be a tricky task as there are many factors to consider when determining which type is right for the job.

First, you must consider the physical size of the inductor and its relationship to other components in your system. You also need to take into account what frequency range you’ll need and how much power it will have to handle.

Additionally, the intended application of your circuit may require more than one type of inductor, so make sure you understand how they all work together and select accordingly.

Finally, be aware that different manufacturers build their products differently; some will use thicker wire or additional insulation for higher reliability or longer life-span. Make sure you research each product thoroughly before making a selection. [3]

Pros and Cons of a Coupled Inductor

A coupled inductor is a type of transformer that links two independent electrical circuits.

It sends energy, typically in the form of an alternating current (AC), from one circuit to another with minimal power loss. Coupled inductors are commonly used in AC power conversion, voltage regulation, impedance matching and signal isolation applications.

Pros and Cons of a Coupled Inductor

The main advantage of using a coupled inductor is its ability to transfer energy with very little energy loss due to the lack of physical contact between the circuits. The design also allows for more efficient and reliable electrical connections as well as improved durability.

However, there are some potential drawbacks to using a coupled inductor. Such designs require larger footprints or enclosures compared to other types of transformers and can be more expensive. They are also limited in terms of their power handling capabilities and the frequencies over which they can operate. In addition, due to the physical separation of the circuits, a coupled inductor cannot be used to provide electrical isolation between the two.

Overall, coupled inductors can be an effective and efficient option for transferring energy between two independent electrical circuits. By weighing the advantages and disadvantages of this type of transformer, users can determine whether it is suitable for their specific application.

Other Types of Inductors

Inductors are a type of electrical component that can be used for many different applications.

In addition to the coupled inductor, there are several other types of inductors available.

Common examples of these include air core inductors, ferrite core inductors, and toroidal inductors.

  • Air core inductors are composed of a coil with no magnetic material around it so that the only magnetic field is generated by the current flowing through the wire windings.
  • Ferrite core inductors use a ferromagnetic material to increase the amount of magnetic field produced; this increases their efficiency and decreases their size.
  • Toroidal inductors wrap a single loop of wire around a doughnut-shaped soft ferromagnetic core, forming an effective magnetic field for the component.

Each type of inductor serves a different purpose, and understanding these differences is essential when deciding which type of inductor to use in an electrical system or circuit. Choosing the right type of inductor can be critical for both performance and cost-effectiveness. For example, a ferrite core inductor may offer better efficiency than an air core inductor but it also may be more expensive. Thus, careful consideration must be taken when selecting the best option for any given application. [4]

Other Types of Inductors

Why Are Inductors Not Used in DC Circuits?

Inductors are not used in DC circuits because they oppose, or increase the resistance of, changes in current. When a constant DC voltage is applied to an inductor, no current flows through it since there is no change in current for the inductor to react to. In AC circuits, however, the changing direction of the current induces an opposing EMF (electromotive force) within the inductor which results in energy being stored and released as needed. This behavior is what makes inductors useful in both AC and coupled inductor circuits.

Coupled Inductors are two separate coils that are wound around a common core material with each coil being electrically isolated from one another but connected magnetically – allowing them to interact with each other. By varying the number of turns, material used in the core, and the spacing between coils, it is possible to create inductors that are tailored to specific requirements and behaviors. Coupled inductors are often used in AC circuits as they allow for greater control over energy transfer than a single inductor alone can provide.

In conclusion, coupled inductors have unique characteristics that make them useful in AC circuits while not being suitable for DC applications. They are efficient at transferring energy between two coils while providing more flexibility when compared to using a single coil alone. Their ability to be tailored to exacting specifications makes them an essential component in many types of electronic devices. By understanding how a coupled inductor works, engineers can use them to design circuits with greater control, accuracy, and efficiency. [5]

Why Are Inductors Not Used in DC Circuits?


What does a coupled inductor do?

A coupled inductor is a type of electrical device that uses electromagnetic induction to couple two or more inductors together.

This means they are able to transfer energy between them without the use of an external power source. Coupled inductors can be used in many applications, such as power supplies, frequency-dependent filters, and oscillators. Additionally, coupled inductors can also be used for impedance matching purposes. The coupling between the two coils can be adjusted by changing the relative position of each coil with respect to one another, allowing for precise tuning of the desired parameters. This makes them extremely useful in a variety of different circuits and applications.

What is the difference between a coupled and an uncoupled inductor?

A coupled inductor is a type of two-coil transformer that can transfer energy between two or more coils. Unlike an uncoupled inductor, which only has one coil, the coupled inductor allows energy to be exchanged between them without the need for an external power source. Additionally, the coupling factor between the two coils can be adjusted by placing them in different positions relative to one another, allowing for precise tuning of the parameters. An uncoupled inductor does not have this same level of flexibility and control.

How do you calculate the coupling coefficient?

The coupling coefficient (also known as “K”) is used to determine how tightly the two coils are coupled together. It is calculated using the following equation: K = (M/L1 x L2)^(1/2). In this equation, M is the mutual inductance between the two coils and L1 and L2 are the individual coil inductances. This can be used to calculate how well energy will transfer between them or how much they will be affected by each other’s magnetic fields.

Are coupled inductors directional?

Coupled inductors are generally not directional, meaning they do not favor one direction of current flow over another. However, depending on their design and use in a particular circuit, it is possible for them to become directionally biased – meaning that one of the coils may favor current flowing in one direction more than another. It is important to take this into account when designing a circuit and to check the manufacturers’ specifications to ensure that it behaves as intended.

What is the difference between an air core inductor and a ferromagnetic core inductor?

An air core inductor consists of one or more insulated coils wrapped around a hollow, non-magnetic form – usually made from plastic or metal. Due to their lack of magnetic material, these inductors have very low levels of reactance, meaning they can be used for high frequency applications. Ferromagnetic core inductors on the other hand consist of one or more insulated coils wound around a solid magnetic material such as iron, steel, or nickel alloy. These materials give the inductor greater levels of reactance which makes them better suited for use in low frequency applications.

What are the advantages of using a coupled inductor?

Coupled inductors offer several advantages over their single-coil counterparts. Firstly, they can transfer energy between two or more coils without the need for an external power source. This makes them ideal for use in circuits where power efficiency is paramount. Secondly, they can be adjusted to provide precise levels of coupling and impedance matching – something which cannot be done with single-coil devices. Finally, they can be used as either a series or parallel component, allowing designers to easily configure circuits according to their needs.

Are there any disadvantages of using a coupled inductor?

The main disadvantage of using a coupled inductor is that the coupling factor can be difficult to adjust and maintain. Due to this, coupled inductors usually require more time and effort to produce than their single-coil counterparts. Additionally, they are typically more expensive due to the need for additional components or materials in order to create the desired levels of coupling. Finally, they may have a greater effect on the performance of other components in a circuit depending on how they are arranged. Ultimately, when considering whether to use a coupled or an uncoupled inductor, it is important to weigh up all the advantages and disadvantages in order to determine which option best suits your needs.

What is the difference between a coupled inductor and transformer?

A coupled inductor is a type of electromagnetic device composed of two or more coils that are mechanically linked together. All the coil windings may be located on one physical core, or each winding can be separately wound around its own core. The purpose of a coupled inductor is to link electric energy between two circuits without any direct electrical connection. A transformer, on the other hand, consists of two or more separate coils wound onto a common magnetic core and electrically connected to each other via their respective windings. Transformers are used to increase or decrease voltage in an AC circuit while providing electrical isolation between input and output. The primary difference between a coupled inductor and a transformer is that the former does not provide any electrical isolation between input and output, while the latter does.

Why do inductors pass only DC voltage?

A coupled inductor is a device that uses two or more coils of wire to transfer energy from one circuit to another. This type of component is used in many types of electronics, such as DC-to-AC and AC-to-DC power converters, radio frequency amplifiers, and electromagnetic interference filters. Although the two coils are electrically connected, they are physically separated by a thin core material such as ferrite or iron powder. This helps keep the magnetic fields produced by the coils from interfering with each other. Inductors pass only DC voltage because they store electrical energy in the form of a magnetic field when an alternating current passes through them. When the current is cut off, this stored energy dissipates back into the inductor, creating a voltage drop. This is why inductors are used to filter and regulate DC voltages in electrical circuits.

Useful Video: Coupled Inductor Basics


A coupled inductor is a device that can be used to provide electrical coupling between two circuits. It is composed of two or more coils, each with its own core and winding, connected in such a way that the voltage induced in one coil creates an electromotive force in the other. Coupled inductors are widely used for various applications, including impedance matching, power supply filters, and signal transmission. They can also serve as transformers to transfer AC signals from one circuit to another without any direct electrical connection between them. By using coupled inductors properly, engineers can create efficient and reliable systems with increased performance characteristics.

In conclusion, a coupled inductor is an important tool for many electronics projects and has many different uses depending on the application. It is an essential component of a wide variety of electrical systems and can help engineers to optimize their designs for increased performance and reliability. With careful consideration, coupled inductors can provide excellent results and make the design process much easier.


  1. https://www.coilcraft.com/en-us/edu/series/a-guide-to-coupled-inductors/
  2. https://www.elprocus.com/coupled-inductor/
  3. https://www.analog.com/en/technical-articles/the-benefits-of-the-coupled-inductor-technology.html
  4. https://www.tdk-electronics.tdk.com/en/2853756/products/product-catalog/inductors-coils/smt-power-inductors/coupled-inductors
  5. https://electronics.stackexchange.com/questions/96648/what-is-the-difference-between-a-transformer-and-a-coupled-inductor