silly question???????how to design a filter???

[indeterminable]

hi, guys


m new to tronix...if we have been given all possible required components for designing a filter...( it may be any filter high,low,etc...) then how to design it....


suppose m not familiar with butterworth or others filters ?????

actually i want to know what would would have possibly came into the mind of butterworth or any other inventors of filter that they designed it in that way ...and we r being taught it as a basic..


the question may be silly ...but plz let me know...


thanks

 

[flatulent]

You have to start with the frequency response you want. What frequencies are passed and how well are they passed (ripple). Then you have to decide what frequencies are stopped and how well they are stopped (attenuation).


Then you select a mathematical approximation (butterworth, chebychev, thompson, elliptical, etc.)

Then you select a technology (passive LC, active, transmission line, digital signal processing, etc.)

**broken link removed** is a free LC filter program you can play with. Try different types (high pass, low pass, bandpass, band stop) and different ripples and attenuations.

Some History: back around 1920 image parameters were invented. These were the first filters ever. Then Darlington discovered a synthesis method around 1930 and many mathematicians devised mathematical polynomials for the filters. They are named after the inventor. This was called "modern filter theory."

 

[indeterminable]

how to design a filter???

hi,


thanks a lot for ur nice prompt reply...

"Then you select a mathematical approximation (butterworth, chebychev, thompson, elliptical, etc.)"

can u tell me how to derive or develop a mathematical approximation before designing any circuit....

meaning to say "is there any way (other than hit and trial) for the for deriving the aforesaid mathematical approximation without knowing the circuit...

thanks agains.....


"wish u good luck"

 

[flatulent]

Very talented people have been developing these polynomials over the last 70 years. It is unlikely that anyone will devise a new one that is better. These polynomials have different advantages and disadvantages.

Butterworth is a compromise between in band ripple and stop band attenuation.

Chebychev has in band ripple but better stop band attenuation.

Elliptical has the best compromise between in band ripple and stop band attenuation.

Thompson-gaussian-bessel have the best phase response.

There is also equal ripple phase.

The last two above have the best pulse shapes.

It is just a matter of what parameters are most important to you.

 

[indeterminable]

hi sir,

thank u very much for ur precious time which u wasted for me....


thanks....

bye

 

[mhtplsh]

U want to design active or passive filter design. Excellent literature available on national & texas instruments websites. This will help u to understand them easily. Many free softwares r also available on net including our own forum.

 

[The Joy of Electronics]

If U R not familiar with the formal procedure of designing filters then u can use matlab. There u only have to specify some parameters and the filter will be worked out.

 

[Meridian]

hi sir,

thank u very much for ur precious time which u wasted for me....


thanks....

bye

My gosh, don't be so hard on yourself. We all started learning that way; asking questions, lots of them and stupid or not is irrelevant.

 

[m.shaker]

you must determine you question. what type of filter you want to design ( active- passive)

 

[flatulent]

to Meridian

Many people on this site do not have English as their native language. It is common for them to translate words from their primary language into English with imprecise results.

In most philosophical-spiritual-religious belief systems it is believed that time spent being beneficial to others is time well spent that will later provide blessings to the person who helped others.