# Kirchoff's law Question

Discussion in 'Homework Help' started by Malsch, Apr 28, 2012.

1. ### Malsch Thread Starter New Member

Mar 19, 2011
23
0
Hi, I was trying to understand how the transfer function is derived from a sallen-key topology using this pdf on page 2: http://www.vyssotski.ch/BasicsOfInstrumentation/AnalysisOfTheSallen-KeyArchitecture.pdf

He starts by using kirchoffs law to obtain equations at certain points. What i was wondering is, at equation 1, how does the author conclude to such results when kirchoffs law states that at a node, all the currents are equal to zero.

Thanks

2. ### Malsch Thread Starter New Member

Mar 19, 2011
23
0
Never mind. he is actually taking them equal to zero. sorry for the stupid question

3. ### Jony130 AAC Fanatic!

Feb 17, 2009
3,990
1,115
Look at those two figures.

The first diagram show I Kirchhoff's law.

Current entering the node must be equal the current that is leaving the node.

And this diagram show II Kirchhoff Law

Last edited: Dec 13, 2015
panic mode likes this.
4. ### panic mode Senior Member

Oct 10, 2011
1,328
305
nice pictures...