Designing of passband and stopband frequencies

1. What is passband and stopband frequencies?
2. What is stopband frequency?
3. What is passband and stopband ripple?

What is passband and stopband frequencies?

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.

What is 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.

What is passband and stopband ripple?

Passband ripple occurs in the high-gain region of a higher-order filter or amplifier's transfer function, and looks like some variations in the output gain. The same applies to the phase on the output. In effect, the two are not smooth functions of frequency. Ripple can also appear in the stopband in these circuits.