Inductance is by no means the easiest of concepts to get to grips with when it comes to circuit design. Nonetheless, it is essential for circuit designers to understand what inductance is and its potential implications for their projects.

If you don’t take steps to demystify inductance, you won’t be able to design high-performance and reliable circuits.

So, below, we have started from the very beginning in explaining inductance, the types of inductance, and why this topic matters in circuit design.

What Is Inductance?

The term “inductance” refers to the property of an electrical conductor – typically a coil or an inductor – that opposes changes in current flow by generating a voltage proportional to the rate of change of current.

When you come across the term “inductor”, then, this is essentially referring to a coil of wire – sometimes wrapped around a core – that resists changes in the electric current flowing through it. You might have also seen inductors described as “coils”, “chokes”, or “reactors”.

The process of current flowing through a coil of wire causes a magnetic field to be created around it. In the event of the current changing, the surrounding magnetic field will also change. This, in turn, will result in a voltage that opposes the change.

What Unit Is Used to Measure Inductance?

Inductance is measured in Henries (H). This unit is named after American physicist Joseph Henry (1797-1878), who discovered electromagnetic induction.

Specifically, one henry is the value of self-inductance in a closed circuit or coil in which one volt is produced by a variation of the inducing current of one ampere per second.

What Are the Different Types of Inductance?

As a circuit designer, you should be aware of such forms of inductance as:

• Self-inductance, which is the voltage induced in a single conductor or coil as a result of its own changing current
• Mutual inductance, which describes how a changing current in one coil induces a voltage in another coil close by
• Parasitic inductance, which refers to unintended and unwanted inductance in circuit traces or components, resulting from their physical construction and layout.

Why Do Circuit Designers Need to Know About Inductance?

If you are involved in circuit design projects, you can’t avoid the topic of inductance. It is a fundamental property of electrical circuits, exerting a profound effect on current flow and signal integrity – particularly at high frequencies.

Here are a few specific reasons why, as a circuit designer, you need to care about and understand inductance:

• Inductance Opposes Changes in Current

As we explained above, inductors resist changes in electric current flow. There are some applications – such as the filtering of noise – where this can be beneficial. However, problems can arise if inductance isn’t managed properly.

• The Need to Ensure Signal Integrity

In high-speed circuits, the aforementioned parasitic inductance can lead to signal reflections, ringing, and timing issues. This, in turn, can detrimentally impact on performance.

• The Implications for Component Selection

While inductors serve as discrete components, even traces on a printed circuit board (PCB) exhibit inductance. This further underscores the importance of understanding the inductance of components and traces, a factor that flexible circuit board manufacturers also consider to ensure the proper functioning of circuits.

• The Potential Impact on Power Delivery

Inductance has an impact on how power is delivered to circuits, especially in switched-mode power supplies. When circuit designers have an in-depth understanding of inductance, this will help them optimise power delivery and make sure their circuit is stable in operation.

Inductance Plays a Pivotal Role in Circuit Design Projects

The above factors are far from the only reasons why you might need to reach for an online inductance unit converter – such as the one on the RS website – to assist you in calculating inductance for a given circuit design.

Nonetheless, we hope this article has given you a good all-round idea of why the concept of inductance is so important for circuit designers to understand. This, in turn, should serve as a sound foundation for further reading.