Looking for 20 db notch filter

[Dick Cappels]

I am looking for a compact and low power filter for a consumer product that can provide better than 20 db attenuation in a notch stretching over an octave. The more highly integrated the better -can anybody recommend an integrated filter or a neat circuit trick that can achieve this with very few parts?

 

[Misterbenn]

what signal level, what frequency

 

[JimB]

in a notch stretching over an octave

That is hardly a notch filter, more a bandstop filter.

JimB

 

[ronsimpson]

Notch filter; Do you want to remove one tone like 440hz or one octave like 1khz to 2khz?

 

[KeepItSimpleStupid]

Power supplies available? Input levels?

 

[Dick Cappels]

I guess the power supply has to be known in order to recommend and IC. The power source will the a single Li-ion cell and I am hopeful that I an use it without a regulator, so it would operate from 4.2 down to about 3.5 volts.

It need to reduce a broad resonant peak between 200 Hz and 350 Hz by about 20 db and another one from about 5 kHz to 8 kHz.

The input signal will come from a preamplifier that will be designed to drive the filter.

The LMC835 looks like it would work but it needs a lot of parts and some digital device such as a microcontroller to set it up at power-on.

Analog Devices has a good DSP solution but I have a tight deadline and no time to learn their development platform.

Any ideas will be welcomed.

 

[Nigel Goodwin]

Well your requirements are still pretty vague, but what you want isn't a notch filter - it's simply a combined low-pass and high pass filter - in fact two of them, a pair for each band you want to attenuate.

So a handful of opamps and passive components.

 

[crutschow]

Deleted post.