ADC with correct decimator?

[dmills]

Hi all,
Just a quick request to pick folks brains...

I am in the middle of working up a multi channel ADC board for a instrumentation application and am having a lot of trouble finding a 24 bit ADC part that handles the decimation filtering correctly.

Every data sheet I have looked at so far uses half band filters (-6db at Fs/2) which is pretty horrible.

Now I could run the converter at a very much higher sample rate and decimate in a small dsp part, but surely someone must be making a part that actually has the stop band starting at Fs/2?

On the DAC side, I have found that the new wolfson part has a few filters that look usable, but they don't have an ADC that has the equivalent filtering.

If anyone knows of something reasonably current that gets this right, please speak up.

Thanks.

Regards, Dan.