[SI-LIST] Re: PDN frequency target
- From: "martinos72" <oscar.martinelli@xxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Mon, 01 Oct 2012 13:33:34 -0000
Dear ALL,
thank you for your prompt reply.
I just would like to stress the fact, if it is possible to get same usefull
information from the sub-paramenter L_pkg (power pins) included in the ibis
file.
First of all: is L_pkg rapresenting the partial inductance of the current path
from the ball to the die ? (es. for a BGA package).
If this would be the case the max. loop inductance would be:
L_pkg power + L_pkg return - 2*L_pkg mutual.
"L_pkg mutual" is going to be the most relavant and difficult value to get. Is
it possible in your opinion make any assumption as rule of thumb to get this
value?
For example,if:
L_pkg power = L_pkg return = 4nH (min.),
L_pkg mutual = 70% of L_pkg power = 2.8nH
Number of power/gnd couple = 15
Z_target = 90 mOhm
The total Loop_pkg_inductance = (4 + 4 - 2* 2.8)/15 = 0.16 nH
From Z= 2*pi*freq.*L we get Freq = Z/(2*pi*L)= 0.09/(2*3.14*0.16nH) = 90Mhz
This is the max frequency the PDN should take care (or even less if we also
include the PCB/package mounting loop inductance that it should be easy to
determing).
Please let me know if in your opinion i'm doing something wrong.
Regards,
OSCAR
--- In si-list@xxxxxxxxxxxxxxx, "martinos72" <oscar.martinelli@...> wrote:
>
> Dear All,
>
> I was wondering if someone could suggest a way to estimate the maximum
> frequency (f target) up to a PDN impedance should be kept under a certain
> level (z target).
>
> According to Dr. Bogatin's brilliant book "si e pi integrity - simplified"
> chapter 13 has been suggested that 100 Mhz should be fine if not otherwise
> specify, but i would like to been able to find out this limit on my own.
>
> From the ibis the parameter L_pkg shouldn't be very useful because seems to
> represent only a partial inductance (am i right?).
>
> Any idea?
>
> Kind regards,
>
> Oscar
>
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