Help; 2nd Order LPF

Discussion in 'Homework Help' started by FanTom4EvEr, Dec 30, 2010.

  1. FanTom4EvEr

    Thread Starter New Member

    Dec 27, 2010
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    0
    Hey guys,

    I have to design 2nd Order Low Pass Filter with a cutoff frequency 1kHz, in my project but, i don't know if i have found the right circuits yet..

    This is the specs of the project:

    Implement a 2nd order low pass filter with attenuation ≥ 40 db/decade and has one of the following cut-off frequencies (fc): 1 KHz, 2 KHz, 5 KHz, 10 KHz, 20 KHz or 50 KHz.

    and This is the circuits that i have got

    1-
    [​IMG]

    L=2.25052 mHy C=11.25259 µfd R= 10 ohm resistor
    outputs 1k Hz cuttoff frequency .. is that right ?


    2-Butterworth low pass active filter.. which with OpAmp

    I wanna know is that right, any of these circuits is right according to my project specs ?


    Thank you in advance,

     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Is this a class assignment?

    hgmjr
     
  3. FanTom4EvEr

    Thread Starter New Member

    Dec 27, 2010
    4
    0
    yes .... i am supposed to implement the circuit (hardware)
    so, i just want to ensure that i am in the right direction
     
  4. FanTom4EvEr

    Thread Starter New Member

    Dec 27, 2010
    4
    0
    This is the second circuit which i mean


    [​IMG]
     
  5. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    Are you familiar with the concept of "frequency scaling" as it relates to filter design? If not then you should try some googling to find out more about it. In essence, if you have a filter design that fits your filter characteristics but at a frequency different from your target frequency then you can translate it to a new frequency by applying "frequency scaling" techniques.

    hgmjr
     
  6. FanTom4EvEr

    Thread Starter New Member

    Dec 27, 2010
    4
    0
    Thanks, that's really helpful :)

    but, are these circuits are right or even one of them according to my project specs regardless, the frequency which is 1kHz?


     
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