How do you calculate bandwidth of low-pass filter?

The basic difference between the two is that frequency is defined as the rate of radio signal to send and receive communication signals, whereas bandwidth is defined as the difference between the highest and the lowest frequencies of a signal generated .

If you consider an ideal low-pass filter with cut-off frequency of fc, all frequencies greater than fc will be removed. Then it’s bandwidth is equal to fcHz (from 0 up to fc) . The total bandwidth BT is simply twice that: BT=2fc, since we are also considering negative frequencies, from −fc up to fc.

Historically, oscilloscope frequency response tended to approximately follow the rule: Bandwidth x risetime = 0.35 . This corresponds to a 1- or 2-pole filter roll-off in the frequency domain. Today, at the high end, most real-time digital oscilloscopes more closely follow this rule: Bandwidth x rise time = 0.45.

We saw that the rise time of a signal is inversely proportional to its bandwidth and that the product of these two parameters is always approximately 0.35.10 Eki 2019