implementation of a band-pass filter

[MAHYAR239]

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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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

 

[CataM]

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.

 

[MAHYAR239]

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

 

[FvM]

Do you want 5 dB pass band ripple?

 

[MAHYAR239]

Do you want 5 dB pass band ripple?

View attachment 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?

 

[FvM]

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.

 

[MAHYAR239]

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

 

[FvM]

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

 

[CataM]

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

 

[FvM]

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

 

[MAHYAR239]

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