Stopband frequency

A stopband is a band of frequencies, between specified limits, through which a circuit, such as a filter or telephone circuit, does not allow signals to pass, or the attenuation is above the required stopband attenuation level.

1. What is passband and stopband frequency?
2. How do you measure stopband attenuation?
3. What is cutoff frequency of a filter?

What is passband and stopband frequency?

A: Passband is the band of frequencies of the input signal that passes through the filter with an attenuation of less than 3 dB attenuation, while stopband is a band of frequencies of the input signal that are blocked or more highly attenuated by the filter.

How do you measure stopband attenuation?

The stopband attenuation is the difference, in decibels, between the lowest gain in the passband and the highest gain in the stopband. Ideally this would be infinite; the higher the better.

What is cutoff frequency of a filter?

The cutoff frequency, or cutoff, determines where the signal is cut off. Simpler synthesizers have only lowpass filters. If a signal contains frequencies that range from 20 to 4000 Hz and the cutoff frequency is set at 2500 Hz, frequencies above 2500 Hz are filtered.