GDF,
You can cascade 2 RC filters to yield a 2 pole filter.
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The filter characteristics depend on the pole locations. In general, the higher the "Q" (ratio of imaginary to real components of the pole), the sharper the transition region (region between the pass band and stop band) will be, and the higher the overshoot to a step input will be.
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As an example, the Butterworth filter is optimal in the sense that of all filters with monotonic (constant sign of the slope) passband and stopband responses, the Butterworth filter has the flattest passband (lowest value of attenuation in the passband). Its, frequency response is far superior to that of a cascaded RC filter with the same passband and stopband specifications. The poles of a Butterworth filter are equally spaced on a circle in the complex plane. So the Butterworth poles for a 1radian/second cutoff frequency are at .707 +/- j.707.
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Pick up any book on analog filter design for more details.
Regards,
Kral