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Filter Inductor requirement for nRF52832 in DCDC mode

Gaurav

I am design a very compact board for my project and running out of space. For this I am planning to replace two DCDC inductors with a single one. Is it possible to do this without affecting the Radio performance?

Please provide your suggestions.image description

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    No you cannot do that. The second 15nH inductor has an SRF in the gigahertz range and is intended to reduce noise at 2.4GHz. If you look at an SRF curve for the 10uH you will see it becomes conductive due to parasitics at 2.4GHz. However, the current requirements are rather small for the DC/DC circuit and you should be able to use smaller components than those specified in the reference design which will allow you to save some space.

    For instance you can easily do an 0603 for the 10uH, but 0201 for the 15nH and an 0402 for the 1uF. There is even a good selection now of 0201 1uF caps. But you should review the SRF, DCR of the cap before committing to it.

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    No you cannot do that. The second 15nH inductor has an SRF in the gigahertz range and is intended to reduce noise at 2.4GHz. If you look at an SRF curve for the 10uH you will see it becomes conductive due to parasitics at 2.4GHz. However, the current requirements are rather small for the DC/DC circuit and you should be able to use smaller components than those specified in the reference design which will allow you to save some space.

    For instance you can easily do an 0603 for the 10uH, but 0201 for the 15nH and an 0402 for the 1uF. There is even a good selection now of 0201 1uF caps. But you should review the SRF, DCR of the cap before committing to it.

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