| Sampling IF Filters - Comparison |
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In comparison with other filter technologies that can be integrated into a semiconductor chip, the SIF possesses significant performance advantages. For example, the following two Figures illustrate a performance comparison for the SIF with a Switched Capacitor and a gm-C filter. While the gm-C filter can operate over the same frequency range as the SIF, its accuracy is far inferior. Even when the gm-C filter is calibrated, its accuracy is only comparable to that of a Switched Capacitor filter, and is still significantly worse than that of the SIF filter.
Another comparison of importance is that of the transfer function response, including both Magnitude and Group Delay distortion, of a SIF with respect to that of classic filter classes such as Butterworth or Elliptic. As shown in the following Figure, the Magnitude response of the SIF is a “SAW like” brick wall (Blue trace), whereas the Elliptic (Red trace) and Butterworth (Green trace) roll-off over a significant frequency range.
Of even more importance, the Group Delay of the SIF presents no distortion at all. This is shown again in comparison with an Elliptic (Red trace) and a Butterworth (Green trace) Group Delay response in the next Figure. Having no Group Delay distortion means that the SIF filter will not contribute at all to any signal distortion, such as ISI (Inter-Symbol Interference).
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