# transfer function for passive filter

Discussion in 'Homework Help' started by notoriusjt2, Nov 7, 2010.

1. ### notoriusjt2 Thread Starter Member

Feb 4, 2010
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the book gives me

Laplace impedance for a capacitor is Z=V/I=1/Cs

what is the Laplace impedance for an inductor? Z=Ls?

so would Vout=(Zc/R+Zc+ZL)Ein
(1/Cs)/(R+Ls+(1/Cs))
im getting

2. ### mik3 Senior Member

Feb 4, 2008
4,846
63
The correct answers are d and e.

3. ### hgmjr Moderator

Jan 28, 2005
9,030
214
You are so close.

hgmjr

4. ### hgmjr Moderator

Jan 28, 2005
9,030
214
Mik3, Initially I thought as you did. On closer inspection I think you will find that answer e. does not equate to d.

hgmjr

5. ### mik3 Senior Member

Feb 4, 2008
4,846
63
Ohhh, yes you are right. The correct answer is d. The numerator of e should be 1/LC as for e to equal d.

6. ### hgmjr Moderator

Jan 28, 2005
9,030
214
Yeah. Like I said, I initially drew the same erroneous conclusion but then looked closer and realized my ooppss.

hgmjr