Author Topic: Improving Impedance profile in PDN  (Read 2510 times)

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Offline joniengr081Topic starter

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Improving Impedance profile in PDN
« on: August 03, 2023, 10:02:54 am »
Hi, I am simulating impedance profile in Hyperlynx PI. I have attached a profile. The impedance requirement is 0.1 Ohm or below. Which decoupling capacitors I should add of which package in order to have the impedance profile blow 0.1 Ohm.

Offline Feynman

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Re: Improving Impedance profile in PDN
« Reply #1 on: August 04, 2023, 06:14:41 am »
Well, isn't that a question that Hyperlynx PI is supposed to help you finding an answer for?  ;D
And up to what frequency do you need 0,1 Ohm impedance? Chances are that you don't need an impedance below 0,1 Ohm up to 1 GHz, if you don't need your rise times to be significantly faster than roughly 1 ns (slow rise times down as much as practicable).

As a first guess you can add capacitors that have their self-resonant frequency at about your anti-resonance peaks. Any further action will depend on up to what frequency you need the impedance to stay below 0,1 Ohm. But again, a tool like Hyperlynx PI should give you a good answer by playing around.

Online nctnico

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Re: Improving Impedance profile in PDN
« Reply #2 on: August 04, 2023, 01:12:23 pm »
Keep in mind that value is equally important as package size. A higher capacitance in an equal package size will resonate at a lower frequency. So even with equal package sizes, it will help to have different values to get a low impedance over a wide frequency range.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.

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