Analog and Digital Filters, Pros and Cons

[LvW]

The switched capacitor Butterworth lowpass and notch filter ICs I have used (from National Semiconductor) were very accurate. Their frequency is tuned by changing the clock frequency.

Yes - according to my experience, this applies to all SC filter-IC`s..

 

[andre_teprom]

I agree, but on need of a more selective filter, we must to chose another model such as Elliptic, which have zeros too close from poles, implying on tighter requirements concerning to accuracy of inner components of the circuit, and at this specific case the switched capacitor approach would not suffice, but remains a nice choice for most applications.