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Maximum capacitance that can be integrated

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Newbie level 2
Jun 22, 2009
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maximum capacitance per can

Hello all,

i am new to this field. I am trying to develop a DC DC converter with Mosfets and capacitors for low power applications. Which i want to integrate in an ASIC.

I have not selected any specific processes yet. But i am looking for the maximum limit of capacitor that can be integrated (eg. pico F or µF). Also i want the chip to be in a reasonable size (20x20 mm2).

Thanks in advance.

So, the max capacitance could be 40mm2-your circuit size... but do you really want to pay for that cost?

If you want on-chip-only, you will have to be switching
at tens to hundreds of MHz. I embed decoupling as an
opportunistic thing but never let it drive die size. The
energy storage density is generally poor (either the
voltage and Q are low (using MOSFET gates) or the
specific capacitance is (metal plates). But if the area
under the power busses is free, then fill it.

I have seen hundreds of pF in poly/metal/metal on
one large-ish mostly-digital design, and nanofarad-
range Cdg in 1A DC-DC output FETs (most of a die
of roughly the size you speak of).
Thank you for your reply. I am only in the starting stage of designing the converter, and wanted to know how big the cpacitor can be if it is integrated.

As you have mentioned, with such capacitances i may have to work with very high switching frequencies.

or forget about integrating Capacitors and use external ones.

Anyway thanks for you input.

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