# 5th order Butterworth Bandpass Filter Design

1. ## 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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2. ## Re: 5th order Butterworth Bandpass Filter Design

Passive or active?
Impedance? Voltage?

Linear or Switched Capacitor blocks or Digital with filter libraries?

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3. ## Re: 5th order Butterworth Bandpass Filter Design

Originally Posted by mck2102
Hello,
I want to design 5th order butterworth filter.
.............
Which steps can I track?
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.

1 members found this post helpful.

4. ## Re: 5th order Butterworth Bandpass Filter Design

Originally Posted by LvW
Originally Posted by LvW
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.

1 members found this post helpful.

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5. ## Re: 5th order Butterworth Bandpass Filter Design

Originally Posted by SunnySkyguy
Passive or active?
Impedance? Voltage?

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

1 members found this post helpful.

6. ## Re: 5th order Butterworth Bandpass Filter Design

Originally Posted by LvW
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?

1 members found this post helpful.

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7. ## Re: 5th order Butterworth Bandpass Filter Design

Originally Posted by mck2102
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 - - -

Originally Posted by LvW
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).

1 members found this post helpful.

8. ## 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

9. ## 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.
Next, order of filter will be based on your stopband rejection level.

10. ## Re: 5th order Butterworth Bandpass Filter Design

Originally Posted by SunnySkyguy

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.

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