Tool for designing and analysing the analog filters

[patan.gova]

Hello,
Can anyone suggest a tool for desinging and analysing the analog filters.
Thankyou.

 

[Audioguru]

There is not much analysis in an active lowpass or highpass filter. If it has 1 RC then its slope is 6dB per octave, 2 RCs give 12dB per octave, 3 RCs give 18db per octave etc. Google Images has graphs of their responses.

A bandpass filter is more sifficult due to its variable Q. It could have a very narrow peak and it could have steep slopes or gradual slopes.

Many of us use the free and modern LTspice IV simulation program. Here are some of its responses of levels:

 

[WimRFP]

Hello, try a search on filter design software. You will sure find something that is useful. If you designed a filter using such software, you can "test" it in various spice based SW packages. The one mentioned by Audioguro (LTspice) is free and used by many. Now there is also a book on how to use it, published by Würth (not free):
https://www.we-online.com/web/en/el...dukte_pb/fachbuecher/ltspice_iv_simulator.php

If you are into VHF/UHF filters (microstrip), your task may require a (planer) Electro Magnetic simulator (such as HFSS, IE3D (now Hyperlynx) and several others).

 

[LvW]

There is not much analysis in an active lowpass or highpass filter. If it has 1 RC then its slope is 6dB per octave, 2 RCs give 12dB per octave, 3 RCs give 18db per octave etc. Google Images has graphs of their responses.
A bandpass filter is more sifficult due to its variable Q. It could have a very narrow peak and it could have steep slopes or gradual slopes.
:

I think, it`s not that simple.
Active filter design is one of the most challenging task in analog electronics.
And - of course also for lowpass and highpass flters various different Q values have to be considered (not only for band pass filters)

In case you need filter circuits for a degree n>1 you have the choice between
* several approximations (Butterworth, Bessel, Chebyshev, Cauer,...) and
* two basic design strategies (cascade design or direct design based on passive RLC structures - using active component simulation), and
* a few different topologies - depnding on the active device you have selected (opamp, OTA, GIC, transistor).

It is a very challenging task to compute the various parts values for the selected circuit design - and that is the reason for the existence of filter design software.

 

[Audioguru]

For this project Butterworth filters are needed for a flat passband and a sharp corners.

 

[permute]

nuhertz also has a good tool. There is a free edition for small filters as well. There is some documentation to describe the advantages of each of the topologies.

 

[Ow@i$]

agree with LVM filter design is not so easy as it may sound.
well i tried AADE Filter Design tool a free software but quite good actually as it has default designs also so that you can just enter your requirement and see the result.

 

[LvW]

For this project Butterworth filters are needed for a flat passband and a sharp corners.

Very often, we hear in this forum that Butterworth filters would exhibit something like a "sharp corner".
Here, everybody can see this "corner" in comparison with two other approximations:

 

[Audioguru]

The Bessel does not filter very good and the Chebyshev does not have a flat passband. A Butterworth filter is the best one for many applications like this one especially if it was a better filter than this simple one (has more poles).