# Bode plot / amplitude response

#### Tobias Hildebrandt

Joined Jan 1, 2016
44

Hello,

here we are supposed to plot the amplitude and phase response of the circuit above.

The phase response was easy enough, but I cant find the right formula for the amplitude response. I thought it was 20 * lg (1/sqrt(1 + (wCR)^2)), but that didnt get me anywhere. Is there a simple formula to plot the amplitude response?

Tobias

#### shteii01

Joined Feb 19, 2010
4,647
First.
Your graph paper is in Hz. Your formula is in rad/s. w=2*pi*f
Therefore:
f=w/(2*pi)
So.
Did you use frequency in Hz or in rad/s to do your calculations for amplitude in dB?

#### Tobias Hildebrandt

Joined Jan 1, 2016
44

I don't know what just happened, very likely I made a mistake on my calculator, because now I got the correct results. Bizarre, I worked on this for ages.... Oh well.
So the formula works after all.
Thanks anyway.

#### shteii01

Joined Feb 19, 2010
4,647
View attachment 99102
I don't know what just happened, very likely I made a mistake on my calculator, because now I got the correct results. Bizarre, I worked on this for ages.... Oh well.
So the formula works after all.
Thanks anyway.
Sleep deprivation will do that.