Use a practical case to illustrate:
Input a 20MHz, 1V sine wave and enable the oscilloscope's 20MHz bandwidth limit (analog bandwidth limitation),
The amplitude drops to 700mV (-3dB attenuation point), and distortion becomes more pronounced at higher frequencies. The original waveform is restored after disabling the limit.
A square wave with an input of 20MHz and 1V is directly transformed into a sine wave under a 20MHz bandwidth limitation.
