LTC1264 as an LF filter?

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neazoi

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Hello, I design an SDR for LF 136KHz.
I have seen that this LTC1264 can be used as a band pass filter at these frequencies, I would like to know if it is considered to be a good filter compared to a standard LC filter. I consider factors such as dynamic range, loss and band-pass roll-off.
 

SunnySkyguy said:
Four 2nd order filters can be cascaded to make 8th order.

Much more precise than LC filter but for low Q only , <1mV noise , 8th order is very steep.
Click to expand...

I am thinking of using this schematic for 136KHz. I have seen it's low Q, but because the opamp filters are cascaded in this configuration the slope is very steep. This is like kafing a single LC of higher Q isn't it?

Should I use this kind of filter right after the antenna or should I better choose an LC filter like this http://www.wireless.org.uk/images/SW-DDS1.gif (cascaded with an amplifier afterwards). I worry about the intermodulation products, since the active filter right after the antenna may be overloaded by out of band strong signals. A passive LC followed by an amplifier seems safer to me.

Any thoughts?
 

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Should I use this kind of filter right after the antenna or should I better choose an LC filter
Click to expand...
The question is clearly answered by the aliasing paragraph in the datasheet...
 

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