1. Cut-Off Frequency:

Refers to the frequency point where the filter transitions from the passband to the stopband. For low-pass filters and high-pass filters, the cut-off frequency determines the dividing point where the signal can pass or be suppressed; for band-pass filters and band-stop filters, there are two cut-off frequencies, which define the boundaries of the passband or stopband respectively.

2. Bandwidth:

For band-pass filters, the bandwidth refers to the frequency range of the passband, that is, the difference between the two cut-off frequencies; for band-stop filters, the bandwidth refers to the frequency range of the stopband. The bandwidth determines the frequency width that the filter can pass or suppress.

3. Insertion Loss:

Refers to the signal power attenuation caused by the filter in the passband after the filter is connected to the circuit. The smaller the insertion loss, the smaller the influence of the filter on the transmission of the signal.

4. Stopband Attenuation:

Indicates the degree of attenuation of the filter on the signal in the stopband, usually expressed in decibels (dB). The greater the stopband attenuation, the stronger the filter's ability to suppress the signal in the stopband.

5. Ripple:

Refers to the fluctuation of the signal amplitude in the passband of the filter. The smaller the passband ripple, the flatter the frequency characteristics of the filter and the smaller the distortion of signal transmission.