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

• From: "Benny Yan" <zyan@xxxxxxxxxx>
• To: <xuzhengrong@xxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
• Date: Thu, 30 Aug 2007 21:20:29 +0800

```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,=20
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 ), =20
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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=20

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