问了下chatgpt 3.5, 回答如下:

for a digital square wave with 10ns raising/falling edge, what's the minimum
requirement of an oscilloscope to fully capture the signal, in terms of ban
dwidth and sampling rate? and why?

To fully capture a digital square wave with 10ns rising/falling edges, an os
cilloscope with a bandwidth of at least 1 GHz and a sampling rate of at leas
t 10 GS/s would be required.

The reasoning behind this is that the bandwidth of an oscilloscope determine
s the highest frequency component of the signal that it can accurately captu
re. A square wave contains harmonics at multiples of its fundamental frequen
cy, and to accurately capture these harmonics, the oscilloscope's bandwidth
should be at least five times higher than the fundamental frequency. In this
case, the fundamental frequency of the square wave is 50 MHz (1/20 ns), so
the oscilloscope's bandwidth should be at least 250 MHz (5 x 50 MHz) to accu
rately capture the signal.

The sampling rate of the oscilloscope determines how frequently it samples t
he waveform. According to the Nyquist-Shannon sampling theorem, the sampling
rate must be at least twice the bandwidth of the signal to accurately recon
struct the waveform. Therefore, a sampling rate of at least 500 MS/s (2 x 25
0 MHz) would be required. However, to accurately capture the sharp edges of
the square wave, it is recommended to use a sampling rate at least 10 times
higher than the bandwidth, which is why a sampling rate of at least 10 GS/s
is recommended in this case.



【 在 bruin 的大作中提到: 】
: 请教下，这个问题咋回答？10n上升沿，算成50MHz基频，再乘以5，谐波最高取250MHz.
:  所以示波器最低带宽应该至少250MHz? 采样率的话，再double一下，500M/s?
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修改:bruin FROM 222.129.3.*
FROM 222.129.3.*