Improving Impedance profile in PDN

[joniengr081]

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.

[Feynman]

Well, isn't that a question that Hyperlynx PI is supposed to help you finding an answer for? 
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.

[nctnico]

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.