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A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

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Re: A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

#21

Post by tgflynn »

wbraun wrote: post #3

The medium article links to a nature article which explains in depth: https://www.nature.com/articles/s41928-017-0010-z This seems like an interesting development, but the performance gain appears to be limited to low value inductors in the 10's of GHz range. Those inductors are already very small and easily integrated on RF ICs. If you want to miniaturize electronics you need to miniaturize the inductors used in pow…

> If you want to miniaturize electronics you need to miniaturize the inductors used in power conversion

Hasn't that problem mostly been solved already with switch mode power supplies that are pretty small.

With most personal electronics being battery powered these days I'm curious where you see a real need for further reduction in the size of power converters. In other words what technologies or devices are currently limited by the size of their power converters ?

Re: A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

#22

Post by amelius »

daddylonglegs wrote: post #18
wbraun wrote: post #3

The medium article links to a nature article which explains in depth: https://www.nature.com/articles/s41928-017-0010-z This seems like an interesting development, but the performance gain appears to be limited to low value inductors in the 10's of GHz range. Those inductors are already very small and easily integrated on RF ICs. If you want to miniaturize electronics you need to miniaturize the inductors used in pow…

The abstract [1] states that the technique is "purely material-enabled" but that they still laid out their kinetic inductor in a spiral. It would seem to me that a big advantage for these inductors in RF chips would be the lack of coupling to and from external magnetic fields if you used another layout. One of the major limitations of existing planar spiral inductors is that their external magnetic fields will couple…

You can shield the magnetic coupling with materials with high permeability.

Re: A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

#24

Post by foldr »

tgflynn wrote: post #21
wbraun wrote: post #3

The medium article links to a nature article which explains in depth: https://www.nature.com/articles/s41928-017-0010-z This seems like an interesting development, but the performance gain appears to be limited to low value inductors in the 10's of GHz range. Those inductors are already very small and easily integrated on RF ICs. If you want to miniaturize electronics you need to miniaturize the inductors used in pow…

> If you want to miniaturize electronics you need to miniaturize the inductors used in power conversion Hasn't that problem mostly been solved already with switch mode power supplies that are pretty small. With most personal electronics being battery powered these days I'm curious where you see a real need for further reduction in the size of power converters. In other words what technologies or devices are currently…

It would be useful to have lower profile inductors. It's difficult to get inductors less than 1mm high for use with low voltage boost/buck converters. ICs and other passive components can usually sit significantly less high above the board.

Re: A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

#25

Post by as-j »

tgflynn wrote: post #21
wbraun wrote: post #3

The medium article links to a nature article which explains in depth: https://www.nature.com/articles/s41928-017-0010-z This seems like an interesting development, but the performance gain appears to be limited to low value inductors in the 10's of GHz range. Those inductors are already very small and easily integrated on RF ICs. If you want to miniaturize electronics you need to miniaturize the inductors used in pow…

> If you want to miniaturize electronics you need to miniaturize the inductors used in power conversion Hasn't that problem mostly been solved already with switch mode power supplies that are pretty small. With most personal electronics being battery powered these days I'm curious where you see a real need for further reduction in the size of power converters. In other words what technologies or devices are currently…

> Hasn't that problem mostly been solved already with switch mode power supplies that are pretty small.

I waste a ton of board space with power supplies. Not everything is personal electronics with custom ICs* in the volume of an iPhone. So this means on my current design there's power supplies for 1v, 1v8, 2v5, 3v3, ~4v, 5v. Each of these the biggest component is the inductor.

I've sometimes joked, I make power supplies with a computer attached.

Edit: since the volume is low we use off the shelf parts which means we tend to end up with a variety of voltage requirements. And yes...reduction of rails is something that's part of components selection, alas....

Re: A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

#26

Post by a1369209993 »

wbraun wrote: post #3

The medium article links to a nature article which explains in depth: https://www.nature.com/articles/s41928-017-0010-z This seems like an interesting development, but the performance gain appears to be limited to low value inductors in the 10's of GHz range. Those inductors are already very small and easily integrated on RF ICs. If you want to miniaturize electronics you need to miniaturize the inductors used in pow…

I assume the obvious solution of just running power conversion at GHz frequencies would waste too much power as EM radiation, correct?

Re: A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

#27

Post by jmwilson »

tgflynn wrote: post #21
wbraun wrote: post #3

The medium article links to a nature article which explains in depth: https://www.nature.com/articles/s41928-017-0010-z This seems like an interesting development, but the performance gain appears to be limited to low value inductors in the 10's of GHz range. Those inductors are already very small and easily integrated on RF ICs. If you want to miniaturize electronics you need to miniaturize the inductors used in pow…

> If you want to miniaturize electronics you need to miniaturize the inductors used in power conversion Hasn't that problem mostly been solved already with switch mode power supplies that are pretty small. With most personal electronics being battery powered these days I'm curious where you see a real need for further reduction in the size of power converters. In other words what technologies or devices are currently…

> Hasn't that problem mostly been solved already with switch mode power supplies that are pretty small.

Perhaps you are thinking of "wall wart" power supplies that used line-frequency transformers in their rectifier design. These have been replaced and miniaturized by using offline switched-mode power supplies and point-of-load converters, but the magnetic components remain the largest components in these designs.

> With most personal electronics being battery powered these days I'm curious where you see a real need for further reduction in the size of power converters.

It's now common for modern SoC devices to require multiple voltage rails. It may require 3.3 V, 1.35 V, 1.8 V on separate pins and each requires a point-of-load converter for efficiency, and each of these take up board space.

Re: A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

#28

Post by compumike »

a1369209993 wrote: post #26
wbraun wrote: post #3

The medium article links to a nature article which explains in depth: https://www.nature.com/articles/s41928-017-0010-z This seems like an interesting development, but the performance gain appears to be limited to low value inductors in the 10's of GHz range. Those inductors are already very small and easily integrated on RF ICs. If you want to miniaturize electronics you need to miniaturize the inductors used in pow…

I assume the obvious solution of just running power conversion at GHz frequencies would waste too much power as EM radiation, correct?

Low efficiency due to thermal losses in transistors switching.

Re: A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

#29

Post by hetman »

a1369209993 wrote: post #26
wbraun wrote: post #3

The medium article links to a nature article which explains in depth: https://www.nature.com/articles/s41928-017-0010-z This seems like an interesting development, but the performance gain appears to be limited to low value inductors in the 10's of GHz range. Those inductors are already very small and easily integrated on RF ICs. If you want to miniaturize electronics you need to miniaturize the inductors used in pow…

I assume the obvious solution of just running power conversion at GHz frequencies would waste too much power as EM radiation, correct?

At those frequencies you're going to be losing a lot of power in the switching losses of the transistors. Power MOSFETS have very low leakage when fully on or off, the largest loss tends to be during the transition when voltage and current are non zero. Because the speed of that transition is limited, the higher the frequency the more percentage of total time is spent in those transition phases and the higher the losses.

Re: A 189 Year Old Limitation on Inductor Size Has Been Broken (2018)

#30

Post by tgflynn »

as-j wrote: post #25
tgflynn wrote: post #21

Earlier quoted context omitted.

> If you want to miniaturize electronics you need to miniaturize the inductors used in power conversion Hasn't that problem mostly been solved already with switch mode power supplies that are pretty small. With most personal electronics being battery powered these days I'm curious where you see a real need for further reduction in the size of power converters. In other words what technologies or devices are currently…

> Hasn't that problem mostly been solved already with switch mode power supplies that are pretty small. I waste a ton of board space with power supplies. Not everything is personal electronics with custom ICs* in the volume of an iPhone. So this means on my current design there's power supplies for 1v, 1v8, 2v5, 3v3, ~4v, 5v. Each of these the biggest component is the inductor. I've sometimes joked, I make power supp…

Are all of those drawing significant current though ? If you just have some small component with an odd voltage requirement that doesn't need much current couldn't you supply it with something a lot simpler than a dc-dc converter, like maybe a voltage divider or linear regulator ?
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