Hi Oscar, You arenâ??t including the package PDN (package decoupling capacitors, embedded capacitance) here. Package decoupling caps can make the whole loop much shorter. I donâ??t think that the math is so simpleâ?¦ Cristian From: martinos72 <oscar.martinelli@xxxxxxxxxxx> To: si-list@xxxxxxxxxxxxx Sent: Monday, October 1, 2012 9:33:34 AM Subject: [SI-LIST] Re: PDN frequency target 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 > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@... with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@... with 'help' in the Subject field > > > List forum is accessible at: >        http://tech.groups.yahoo.com/group/si-list > > List archives are viewable at:  >       //www.freelists.org/archives/si-list > > Old (prior to June 6, 2001) list archives are viewable at: >       http://www.qsl.net/wb6tpu > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at:        http://tech.groups.yahoo.com/group/si-list List archives are viewable at:        //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at:       http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu