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Design >> RF Design >> Does metal (copper, aluminum) shielding really help inductors in ICs?
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Message started by vlsi_design on Mar 31st, 2022, 11:29am

Title: Does metal (copper, aluminum) shielding really help inductors in ICs?
Post by vlsi_design on Mar 31st, 2022, 11:29am

In ICs, the inductors can magnetically couple to the the substrate and cause eddy current to flow which causes power loss (emf^2/Rsub). To minimize this people put metal (copper, aluminum) shielding below the inductor to prevent magnetic lines of from from reaching substrate. Now the catch is both copper and aluminum have mu_r =1 i.e. they will pass all magnetic lines of force to the substrate. How can they help in shielding magnetic coupling? If iron were used then it might make sense but ICs do not use iron usually. Therefore, what is the mechanism?

Title: Re: Does metal (copper, aluminum) shielding really help inductors in ICs?
Post by Frank Wiedmann on Apr 1st, 2022, 2:26am

I suggest that you take a look at https://www.sonnetsoftware.com/support/downloads/publications/EffPatGndShieldModeling_FinalFinalSubmission-COMCAS.pdf and https://www.sonnetsoftware.com/support/downloads/publications/SiRFIC_Inductor_Si_Induced_Currents-ppt.pdf (as well as https://www.youtube.com/watch?v=gDNp_TZQXcE if you like to get this narrated). This topic was also discussed in the article series "Patterned Ground Shields For Silicon RFICs" accessible from https://www.rfglobalnet.com/author/james-c-rautio.

Title: Re: Does metal (copper, aluminum) shielding really help inductors in ICs?
Post by vlsi_design on Jun 8th, 2022, 8:10am

Thanks a lot Frank.

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