pass band การใช้

Practical filters have non-flat frequency or phase response in the pass band and incomplete suppression of the signal elsewhere.
Given that the filter does not contain any resistive elements, the image impedance in the pass band of the filter is purely imaginary.
The ripple like plot on the upper left is the pass band ripple and the ripple on the bottom right is the stop band ripple.
Note that the transition from the pass band to the stop band is much slower than for other filters, but the group delay is practically constant in the passband.
As a result there are six extremal frequencies, and then we add the pass band and stop band frequencies to give a total of eight extremal frequencies on the plot.