1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Simple RC filters phase question

  1. May 28, 2010 #1
    1. The problem statement, all variables and given/known data
    I'm a bit confused about how to find the phase equation of a lossy low pass filter

    2. Relevant equations
    For a normal low pass filter it's just arctan(wRC)

    3. The attempt at a solution


    So im comparing this by subbing in values and comparing to a bode plot of an actual circuit on a breadboard and a spice version of the circuit. But this is nothing like what i get in spice, i've checked for errors but I think its something wrong with the way im actually calaculating it... but cant figure out why?
  2. jcsd
  3. May 29, 2010 #2
    You multplied by the negative of the conjugate. This will screw up your phase equation.
  4. May 29, 2010 #3
    Oh thanks so much! Worked out fine now. I feel so stupid haha, i soooo wasn't thinking when i did that! I get the exact same thing except in the last line it's +1 not -1. Makes a big difference though.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - Simple filters phase Date
Free Energy of a Simple Quantum System Nov 21, 2017
Susceptibility of a simple metal (Problem 31.6 in Ashcroft's May 14, 2017
Solar cell interference filter Apr 18, 2015