(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Given the coupled RC network shown below (see attachment), show that the voltage transfer function is

[tex]\frac{Vout}{Vin}=\frac{1}{(1-\omega^2C^2R^2)+3j\omega CR}[/tex]

Hint: [tex]\frac{Vout}{Vin}=\frac{V1}{Vin}\frac{Vout}{V1}[/tex]

2. Relevant equations

For Capacitor, [tex]Z=\frac{1}{j\omega C}[/tex]

General Potential divider equation [tex]Vout=\frac{Z2}{Z1+Z2}Vin[/tex]

3. The attempt at a solution

I find this all a bit confusing :( I know that the second filter is acting as a load for the first filter, so I know I just can't write

[tex]V1=\frac{1}{j\omega C}\frac{1}{R+\frac{1}{j\omega C}}Vin[/tex]

So would I need to combine the total impedance of the second filter with the impedance of the first capacitor?

Actually, could someone clear up impedance and reactance? For a capacitor reactance is

[tex]X=\frac{1}{\omega C}[/tex]

while its impedance is

[tex]Z\frac{1}{j\omega C}[/tex]

So if a resitor is connected in series, how/what would I combine to obtain the total resistance/impedance?

Anyhelp would be appreciated, I think you can tell that my ideas are a bit muddled :s

thanks

SG

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Cascaded low pass filters problem

**Physics Forums | Science Articles, Homework Help, Discussion**