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| Why aren’t bypass capacitors built into IC’s? |
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| danielbriggs:
Hi all, After watching Dave’s excellent couple of videos about bypass capacitors... I was left wondering the question “why aren’t bypass / decoupling capacitors built into the IC package if they’re needed for optimal operation? They’d be super close to the die, so that would be a good thing? Is it just space and cost issues preventing this? Or are there any better reasons for this not being the norm. Thanks, Daniel |
| coppice:
It is unusual to put decoupling caps inside the IC package, but decoupling caps on the outside of the package are fairly common for high performance parts. |
| Zero999:
I believe this question has been asked here before, but can't find it. It's because there isn't space in the package and it's just cheaper to put them in externally. EDIT: It's been asked on Stack Exchange, which Google shows on the first hit. I don't know about here. https://www.google.com/search?q=Why+aren%E2%80%99t+bypass+capacitors+built+into+IC%E2%80%99s%3F&ie=utf-8&oe=utf-8&client=firefox-b |
| David Hess:
Sometimes decoupling or other capacitors are added inside the IC package either on the IC or on the lead frame but it is usually more economical to require them externally. |
| KE5FX:
It's becoming more common to see caps inside IC packages. They are not always mentioned in the data sheet, but they can be 'found' if you look. E.g., here's a nice shot of a switching regulator (LT8650S) with both input- and output-side bypassing: And a clock synthesizer chip (LMK61E2): They are present in FPGAs too in some cases (Kintex for sure, and presumably Virtex). I wouldn't be surprised if they're used in SoCs and SDRAM parts as well. |
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