Low Pass Filter voltage gain

Discussion in 'Homework Help' started by Jaywin, Apr 21, 2008.

  1. Jaywin

    Thread Starter New Member

    Apr 20, 2008
    9
    0
    Why the voltage gain will decrease while the frequency is increasing?:confused:
    [​IMG]
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    That is the entire point of a low-pass filter!
    The low frequencies pass right through.
    Frequencies above the passband edge (-3dB point) are attenuated more than 3dB.
    It looks like the passband edge for this filter is at around 1200 to 1500 Hz.
    Likely a Sallen-Key/Butterworth implementation.
     
  3. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    As SgtWookie said, a low pass filter pass the signals with low frequency and attenuates the signals with high frequency.

    Also, a high pass filter pass high frequency signals and attenuates low frequency signals.

    A band-pass filter passes signals with frequencies between a range and attenuates all the other

    what is more, there are stop-band filters which attenuate the frequencies in a certain range and pass all the other.

    just for information man.
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    It is the result of the 10k resistor in series with the 15nF capacitor to ground in your other thread. It is a lowpass filter with a cutoff frequency (-3dB) at 1066Hz.
     
  5. Caveman

    Active Member

    Apr 15, 2008
    471
    0
    It has only -20dB/decade, so it's only one pole. No such thing as a one pole Sallen-Key/Butterworth. Probably just an RC.
     
  6. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    The primary reason for the gain being a function of frequency is that the circuit appears to have a component whose impedance is a function of frequency. The most common components that have this characteristic are inductors or capacitors.

    hgmjr
     
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