I need to filter out frequencies above 25 - 30 kHz (as long as it stays below 30 kHz, it's alright) in an audio signal. Cut-off is around 20 kHz.
At the moment I'm hoping that a passive low-pass filter will do the trick, but I'm uncertain whether the cut-off slope will be steep enough.
Some ripple in the passband is acceptable, as long as it stays below 0.5 dB. Ripple in the stopband of more than 0.5 mV is unacceptable (voltage of supplied signal is 5 V max).
Will a passive filter work, or would an active filter be more suitable? What kind of values for the filter circuit would be needed? I'm looking for a Chebyshev response.
At the moment I'm hoping that a passive low-pass filter will do the trick, but I'm uncertain whether the cut-off slope will be steep enough.
Some ripple in the passband is acceptable, as long as it stays below 0.5 dB. Ripple in the stopband of more than 0.5 mV is unacceptable (voltage of supplied signal is 5 V max).
Will a passive filter work, or would an active filter be more suitable? What kind of values for the filter circuit would be needed? I'm looking for a Chebyshev response.