carlgrace
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Aaron,
That isn't true at all. There are plenty of applications for which analog filters are not only "good enough" but essential. Take for example and RF receiver. There is usually an LNA, mixer, analog filter, then ADC. The question is, how do you spec the required dynamic range of the ADC? Assuming there is enough gain before the ADC, the ADC is specified by looking at the ratio of the peak expected blocker to the desired. In some cases the blockers can be huge. Without a good analog filter, the ADC may require enormous dynamic range and take a lot of power. If you put a good analog filter in front of the ADC, you may be able to knock the blockers down my many dB, and relax the requirements of the ADC. This is much more than simple anti-alias filtering. There are also applications where analog filters are the only way to go due to speed requirements, such as in 10G Ethernet and high performance read channels. There are important uses for both analog and digital filters in integrated systems.
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