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  1. #21
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    Re: implementation of a band-pass filter

    Quote Originally Posted by CataM View Post
    The attenuation will be given by the filter's components. ADS will show what is the attenuation if you use the Filter Design guide...
    I am using that but ... I can't even set my filter order ...
    When I choose a low-pass filter I can set the filter order easily but for a band-pass filter, it doesn't work...
    so I have 2 problems now!
    1- I can't set filter order using Filter Design Guide (N=5, e-r,bans-pass)
    2- then attenuation

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    Quote Originally Posted by FvM View Post
    If you give the known specifications for your filter, we can possibly clarify how far the remaining parameters are already determined by it. Or implement a design example.
    sure, an equal ripple band-pass with a center frequency of 3.5GH and FBW=20%...for 5dB, N=5



  2. #22
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    Re: implementation of a band-pass filter

    Quote Originally Posted by MAHYAR239 View Post
    1- I can't set filter order using Filter Design Guide (N=5, e-r,bans-pass)
    2- then attenuation
    Filter's order gives the attenuation.
    sure, an equal ripple band-pass with a center frequency of 3.5GH and FBW=20%...for 5dB, N=5
    Try with Maximally flat with following parameters:
    Ap=5 dB
    As= 122 dB
    Fs1=0.28 GHz
    Fp1=2.8 GHz
    Fp2=4.2 GHz
    Fs2=42 GHz

    That gives a 5th order Band Pass filter.


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    •   Alt7th May 2017, 14:54

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  3. #23
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    Re: implementation of a band-pass filter

    Quote Originally Posted by CataM View Post
    Filter's order gives the attenuation.

    Try with Maximally flat with following parameters:
    Ap=5 dB
    As= 122 dB
    Fs1=0.28 GHz
    Fp1=2.8 GHz
    Fp2=4.2 GHz
    Fs2=42 GHz

    That gives a 5th order Band Pass filter.
    but it's an equal-ripple one



    •   Alt13th May 2017, 10:14

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  4. #24
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    Re: implementation of a band-pass filter

    Do you want 5 dB pass band ripple?

    Click image for larger version. 

Name:	Chebyshev 3.5 GHz 20% 5th 5dB.gif 
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ID:	138721


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  5. #25
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    Re: implementation of a band-pass filter

    Quote Originally Posted by FvM View Post
    Do you want 5 dB pass band ripple?

    Click image for larger version. 

Name:	Chebyshev 3.5 GHz 20% 5th 5dB.gif 
Views:	6 
Size:	14.0 KB 
ID:	138721
    yes, that's what I want

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    Now, I'm trying to design it using "Passive Circuit DG - Microstrip Circuits" feature of ADS...when click the "design "it shows the following warning ..how can I modify it?Click image for larger version. 

Name:	Capture.PNG 
Views:	4 
Size:	6.2 KB 
ID:	138722



    •   Alt13th May 2017, 13:11

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  6. #26
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    Re: implementation of a band-pass filter

    5 dB ripple is quite high, that's true. It involves particularly a high Q of individual LC sections and respective sensitivity against parameter variations, also possibly extreme L and C values.

    I don't know if it's an exercise or a real hardware design problem.


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  7. #27
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    Re: implementation of a band-pass filter

    I wonder why my manual values of capacitors and inductors are not even close to the values ADS gives ...

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    I got these using ADS:
    Click image for larger version. 

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ID:	138855 andClick image for larger version. 

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ID:	138856
    but I have these values from manual calculations:
    for example : C1 = 0.1066 pF , L1= 19.3919 nH
    What's wrong?



  8. #28
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    Re: implementation of a band-pass filter

    I got similar values as ADS with Nuhertz Filter Solutions. How did you calculate the filter? Same topology, same parameters?


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    •   Alt19th May 2017, 15:03

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  9. #29
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    Re: implementation of a band-pass filter

    It is very difficult to implement a 5th order band pass filter with only 1 pair of capacitor and inductor..


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  10. #30
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    Re: implementation of a band-pass filter

    I see C1 = 0.1066 pF , L1= 19.3919 nH if you design the filter for 0.5 dB pass band ripple.


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  11. #31
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    Re: implementation of a band-pass filter

    I guess I had some mistakes in the manual calculation ...thanks all



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