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    5th order Butterworth Bandpass Filter Design

    Hello,
    I want to design 5th order butterworth filter.
    I have this parameters;
    w1=7kHz
    w2=12kHz
    Order=5
    Type=Butterworth
    Band-pass
    PRW= -
    Which steps can I track?

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    Re: 5th order Butterworth Bandpass Filter Design

    Passive or active?
    Impedance? Voltage?

    Linear or Switched Capacitor blocks or Digital with filter libraries?
    A best design is easily achieved with good test specs™
    A better question deserves a better answer. ™
    ... so include all your acceptance criteria ( values, % tolerance) and assumptions in your question or any design.

    ... Tony Stewart EE since 1975
    - slightly north of Toronto


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    Re: 5th order Butterworth Bandpass Filter Design

    Quote Originally Posted by mck2102 View Post
    Hello,
    I want to design 5th order butterworth filter.
    .............
    Which steps can I track?
    How deep is your knowledge?
    Do you know the difference between several available design strategies active, passive, cascade design, direct design,...)?
    By the way - there is no bandpass of fifth order. The order is determined by the number pole pairs [correction: number of poles] (n=2,4,6..) - and it is not a simple task to design a Butterworth bandpass of order n=4 or n=6.
    Are you allowed to use a filter design program? This would be the best and easiest way for designing such a filter.
    Last edited by LvW; 9th December 2014 at 22:13.


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    Re: 5th order Butterworth Bandpass Filter Design

    Quote Originally Posted by LvW View Post
    How deep is your knowledge?
    Quote Originally Posted by LvW View Post
    Do you know the difference between several available design strategies active, passive, cascade design, direct design,...)?
    By the way - there is no bandpass of fifth order. The order is determined by the number pole pairs [correction: number of poles] (n=2,4,6..) - and it is not a simple task to design a Butterworth bandpass of order n=4 or n=6.
    Are you allowed to use a filter design program? This would be the best and easiest way for designing such a filter.
    I think we can assume BPF=LPF and HPF which are implemented by cascade

    The order can also be implmented in odd numbers using switch cap block filter chips.

    I think the easiest solution uses LTI's 5th order B LPF filter on a chip with adaptation using external RC for HPF, combined using 2 chips and a clock.
    A best design is easily achieved with good test specs™
    A better question deserves a better answer. ™
    ... so include all your acceptance criteria ( values, % tolerance) and assumptions in your question or any design.

    ... Tony Stewart EE since 1975
    - slightly north of Toronto


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    Re: 5th order Butterworth Bandpass Filter Design

    Quote Originally Posted by SunnySkyguy View Post
    Passive or active?
    Impedance? Voltage?

    Linear or Switched Capacitor blocks or Digital with filter libraries?
    -Active
    -I can use impedance that I want


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    Re: 5th order Butterworth Bandpass Filter Design

    Quote Originally Posted by LvW View Post
    How deep is your knowledge?
    Do you know the difference between several available design strategies active, passive, cascade design, direct design,...)?
    By the way - there is no bandpass of fifth order. The order is determined by the number pole pairs [correction: number of poles] (n=2,4,6..) - and it is not a simple task to design a Butterworth bandpass of order n=4 or n=6.
    Are you allowed to use a filter design program? This would be the best and easiest way for designing such a filter.
    I don't have knowlodge much. I can use pspice .
    If This filter will be designed, Can I connect in series 2th low pass and 3th high pass?


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    Re: 5th order Butterworth Bandpass Filter Design

    Quote Originally Posted by mck2102 View Post
    I don't have knowlodge much. I can use pspice .
    If This filter will be designed, Can I connect in series 2th low pass and 3th high pass?
    Of course, you can. However, as a result you will get a 5th order filter having a certain pass band - but it will NOT be a Butterworth bandpass.
    So - what do you really need?

    - - - Updated - - -

    Quote Originally Posted by LvW View Post
    So - what do you really need?
    In particular, you should clarify if you need a filter with 5 poles or 5 pole pairs (terminology is sometimes confusing).
    Last edited by LvW; 10th December 2014 at 11:06.


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    Re: 5th order Butterworth Bandpass Filter Design

    This is a very powerful filter synthesis software:
    http://www.nuhertz.com/software/soft...-filter-module

    There is also a no-cost lite version:
    http://www.nuhertz.com/software/filter-light



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    Re: 5th order Butterworth Bandpass Filter Design

    Hi,
    You need butterworh response then it should not be a LP+HP cascaded and it must BPF only.
    If you not worrying about butterworth resposne, go ahead with LP+HP cascaded.
    Next, order of filter will be based on your stopband rejection level.



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    Re: 5th order Butterworth Bandpass Filter Design

    Quote Originally Posted by SunnySkyguy View Post

    I think we can assume BPF=LPF and HPF which are implemented by cascade

    The order can also be implmented in odd numbers using switch cap block filter chips.

    I think the easiest solution uses LTI's 5th order B LPF filter on a chip with adaptation using external RC for HPF, combined using 2 chips and a clock.

    You may choose any criteria for HP,BP,LP and cascaded in any order as long as interference is tolerated by active part. e.g. 10th order by cascading two LTC1062 chips. http://cds.linear.com/docs/en/datasheet/1062fd.pdf

    3rd order HPF comes in many std. flavors, Salen & Keys ( see bottom image) Multi-Feedback high gain HPF and may be increased in order.
    The LTC1062 may also be adapted with external RC parts to make a 5th Order HPF.

    Design by Parameters include;
    Low side band stop rejection values
    slope on low side, ,
    Band pass criteria ( gain, minimum ripple, , linear phase, maximally flat amplitude, maximally flat group delay, raised cosine) and then band reject on high side.
    slope and phase shift on high side, Q, overshoot, etc.

    Active switch cap RC filters may be any n value or order and may be cascade but limited to practical frequencies of circuit such as 10~ 100kHz.

    Then I might consider using something like below.

    A best design is easily achieved with good test specs™
    A better question deserves a better answer. ™
    ... so include all your acceptance criteria ( values, % tolerance) and assumptions in your question or any design.

    ... Tony Stewart EE since 1975
    - slightly north of Toronto



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