17kHz BanPass filter Chebyshev n order

Discussion in 'The Projects Forum' started by jgjustingino, Apr 30, 2014.

  1. jgjustingino

    Thread Starter New Member

    May 1, 2012
    2
    0
    hello, I'm trying to find more information on designing a 4th order chebychev 1 order band pass filter.

    my filter need to be centered around 17kHz and i'd like it to be 1000kHz or less but all I've found to be useful is a Q=10 with a 1700Hz pass band, witch is livable.
    My real question is I've got information on Butterworth and designing n order circuits but nothing really on chebyshev circuits. So where do I find more on this kind of thing.

    2nd Question: I've read about a multiple feedback active filter and how their good for high Q, up to q=25. Is this the way to go with this project.

    Oh, just to dot the i's. I'm looking for a min attenuation at 15kHz/19KHz of -10dB but I would like it to be greater, so I'm looking for the higher order filter design.
    THanks.
     
  2. richard.cs

    Member

    Mar 3, 2012
    162
    31
    I've used these for a 17.2 kHz VLF receiver (SAQ), they work well but you need some fairly high performance op-amps.
     
  3. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,542
    1,251
    Generally speaking I prefer separate, cascaded highpass and lowpass sections over multi-stage bandpass sections. Better control of, well, everything. In any case, I recommend using filter blocks from the chip vendors. Unless you're just dying to muck around with gyrators, state variables, quadratic sections, etc., here is an example of a group of parts from Linear Tech, Maxim, National (now TI), etc.:

    http://cds.linear.com/docs/en/datasheet/1562fa.pdf

    The circuit on page 16 hits your numbers when scaled for freq.

    What is your application/inband signal/outband signal?

    ak
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,024
    3,236
    If you want to roll your own you might try the free FilterPro program from Texas Instruments.
     
  5. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,648
    764
    Or FilterLab from Microchip. Simple to use.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    If you'd like to try an LC filter, I suggest you download Elsie here: http://tonnesoftware.com/elsie.html
    It has a Freeware/Student mode for up to 7th order filters.

    Here's an example schematic I had it generate for your requirements (note that impedance is 50 Ohms)

    [​IMG]

    Example transmitted & reflected energy plots attached. Note that learning to tune LC filters takes a fair amount of effort; they aren't something that you can simply throw together.
     
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