Samsung’s Claim of “World’s Smallest Power Inductor” Has Big Design ImplicationsSeptember 24, 2020 by Jake Hertz
This month, Samsung released news of the "world’s smallest power inductor." What does this miniaturization mean for electronic design, even at a theoretical level?
Any engineer who has taken EE101 was likely introduced to circuitry first with a simple voltage source and resistor network. Once that was fully covered, they’d move on to capacitors—a little abstract, but straightforward enough to understand.
Then, they are introduced to inductors, the storage of energy in the form of a magnetic field, and a source of resistance to a change in current. This is where things start to get strange.
A basic inductor is a coiled wire, which concentrates magnetic field lines in this diagrammed sructure.
Inductors are a fundamental electrical component that strikes fear in the hearts of many students and young engineers. Yet their importance can’t be overstated. Our entire electrical infrastructure is based on the same EM principles that inductors operate under. Inductors are ubiquitous in essential circuit blocks, particularly power supplies.
They're also at the forefront of new research and development—for instance, researchers at the University of Illinois, Urbana-Champaign recently created a method to combine inductors and capacitors. An even larger announcement on inductors came from Samsung this month, which claimed that it has created the industry's smallest power inductor.
What's the significance of Samsung's claim and what are the hands-on implications for the electrical engineer?
Inductors in Power Supplies
In popular power supply architectures, like the buck/boost converter, an inductor is a critical component.
In this circuit block, the inductor at the input works to resist sudden variations in input current. When the MOSFET is turned on, the inductor stores energy from the input in the form of a magnetic field, and discharges it when MOSFET is closed.
Simplified inverting buck/boost converter topology. Image used courtesy of Alex Feng
This topology is so popular because it is extremely efficient compared to something like a linear inverter that relies on resistive divider networks, which dissipate significant power. This topology also provides the ability to either buck (lower) or boost (raise) the input voltage to reach the desired output voltage, meaning this topology can handle wide variations in the input voltage.
Trends In Power Supply Design
As chips and other electronic devices have scaled down, power supplies have scaled down as well. In fact, many researchers in the field of VLSI are currently working on ways to miniaturize power supplies such that they can be integrated on chip as opposed to off chip like is common today.
Miniaturizing power supplies, both on and off chip, would increase system efficiency and response time because the supply could be placed closer to the load, eliminating the effects of parasitics along the power delivery network.
Unfortunately, the major roadblock here is—you guessed it—the inductor. Inductors are hard to miniaturize because the value of their inductance is proportionally related to the area of the coil and the number of turns in the coil. Popular methods to manufacture inductors, both on and off chip, simply don’t lend well to miniaturization.
A spiral inductor, one of the most common means of creating inductors on-chip. Image used courtesy of Stavros Iezekiel
Additionally, improved component specs mean increased power usage, necessitating power inductors that can withstand high currents.
Samsung’s Announces "World's Smallest Power Inductor"
With these issues in mind, researchers at Samsung Electro-Mechanics have developed new power inductors that they claim are the smallest power inductors in the world. These new power inductors are of the 0804 size, 0.8 mm x 0.4 mm x .64 mm, which is drastically smaller than Samsung’s previously smallest product sized 1.2 mm x 1.0 mm x 0.65 mm.
New power inductors from Samsung. Image used courtesy of Samsung
According to Samsung, miniaturization was made possible by a newly-developed material that applies nano-grade, ultra-microscopic powder. This powder enables finely spaced coils by applying dimming technology, a manufacturing method using light to mark circuits.
The Opportunities Miniaturized Inductors Afford
The need for smaller power supply circuits has become paramount as devices, both on the chip level and the device level, have miniaturized.
To this point, one of the fundamental roadblocks in miniaturizing popular power supply architectures, like the buck/boost converter, has been the inductor. Now, with Samsung’s recent news, it seems hopeful that miniaturizing inductors is becoming more of a possibility.
With smaller inductors and hence smaller power supplies, engineers will be able to create circuits with better efficiencies and better reliability, thanks to improved response times and less parasitic loss.
Samsung comments that their R&D into miniaturized inductors comes at a timely moment: “With the high-performance and multifunctionality of electronic devices, activation of 5G telecommunications, and growth of the wearable device market, the demand for super-small power inductors is expected to grow at a rapid pace, and its installment within electronic devices is forecasted to grow by at least 20% per year.”