# Homework Help: How to get this expression from the circuit

1. Apr 14, 2010

### nhrock3

it is given that R1=R2

http://i43.tinypic.com/b8359w.jpg
i used voltage divider
i tried to calculate it by taking v1 as the midle poit of the left brench
and v2 as the middle point of the of the other branch

so Vout=V_s/2 -Vs[r/(r+1/jwc )=v_s/2(1-rjwc/2(rjwc+1))

i cant get the expression in the photo

2. Apr 14, 2010

### Staff: Mentor

I get the expression in the photo, so it must just be an algebra problem in your work. Be careful with your parenthesis when writing it out like you did above... the last expression is missing some parenthesis that make a difference.

In Latex:

$$V_o = V_s (\frac{1}{2} - \frac{R}{R + \frac{1}{jwC}})$$

$$V_o = V_s (\frac{1}{2} - \frac{R}{\frac{jwRC}{jwC} + \frac{1}{jwC}})$$

... and so on ...

Last edited: Apr 14, 2010