Opt49LP

Application

·This response shape has found wide acceptance as an alias protection filter for applications where analysis is carried out in the frequency domain (e.g. FFT analysis), and wide sampled bandwidth is more important than the time history of the waveform. Minimum suggested sample rate is 2.5 times the filter cutoff frequency.


Description

The Opt49LP  response is a modified elliptic filter; Opt49LP has a flat passband with ripple of less than ±0.1dB up to the cutoff frequency, and a stopband of -77dB starting at 1.5 times cutoff (figures 3 and 4). The phase response of such filters is quite non-linear (shown in figures 2,6,7 and 9). See figures 1 and 5, and the table overleaf, for details of overshoot and settling behaviour.