## [SI-LIST] Re: the difference of current profile between power supply path, signal path and return path in a circuit loop

• From: xuzhengrong <xuzhengrong@xxxxxxxxxx>
• To: 'Benny Yan' <zyan@xxxxxxxxxx>
• Date: Fri, 31 Aug 2007 10:14:00 +0800

Benny,
I know my question is so basic and seems to be ridiculous.
What I interest is how to get the current profile for voltage noise
simulation associated with PDN, for it is hard to get the current =
profile of
ICs in the power rail from IC supplier.
Though there's a method to get current profile by voltage tests =
indirectly,
I'm still interested in getting it by direct tests.
So I ponder upon the problem whether it exits a path I can test simply =
and
accurately?

Zhengrong

=B7=A2=BC=FE=C8=CB: Benny Yan [mailto:zyan@xxxxxxxxxx]=20
=B7=A2=CB=CD=CA=B1=BC=E4: 2007=C4=EA8=D4=C230=C8=D5 21:20
=CA=D5=BC=FE=C8=CB: xuzhengrong@xxxxxxxxxx; si-list@xxxxxxxxxxxxx
=D6=F7=CC=E2: RE: [SI-LIST] the difference of current profile between =
power supply
path, signal path and return path in a circuit loop

Forgot Kirchhoff's current law?
=20

Benny Yan
IO Methodology Inc.=20

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On
Behalf Of xuzhengrong
Sent: Thursday, August 30, 2007 8:34 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] the difference of current profile between power =
supply
path, signal path and return path in a circuit loop

Hi all,
After scanning the discussion about the return path,  I  have to think =
such
a question that, what does the  current profile in power supply, signal =
path
and return path in a circuit loop look like, and what is the difference =
of
the three ones?
As is known to all,  in a simple DC circuit such as small bulb loop, =
current
supply is equal to the return current between possive pole and negative
pole.
Then, in a high speed digital circuit,  if only one buffer works and =
outputs
one signal level(excluding multi-signal use the common return path and =
power
supply path ), would current profiles in the signal path and its return =
path
be the same?
Furthermore,  as the source of the signal current,  what is the =
difference
between  the current profile in the power supply path and its signal =
current
profile?

Thanks for any idea.

Zhengrong

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