Filter Design Wizard - Low Pass Filters
Problem:
How does a designer implement a low pass filter?
Solution:
When a low pass filter is implemented, there will be a range of frequencies from DC (or near DC) up, where the the amplitude is
constant. Then, a slow roll-off will begin, which will increase to a final slope:
Design Procedure:
- Begin with the desired gain for the majority of the low frequency band (the flat region).
- Given that there will be roll-off at high frequencies, select the lowest frequency for which a 3 dB (or 70.8%) amplitude roll-off is
acceptable.
- At ten times the frequency selected in the step above, is 20 dB (10 times rejection) acceptable, or would 40 dB (100 times rejection) be better?