Question about buying an oscilloscope: Is having more than 100MHz BW useful if the sampling rate is 1Gs/s?

Thread Starter

EnzoEngr

Joined Nov 7, 2022
5
Some available models that are 100MHz-200MHz BW and 1 Gs/s seem to fit my current budget. However, for 1 Gs/s, a 50MHz signal only has about 20 samples per period. So, this causes any BW more than 100MHz not to be useful since any signal >50MHz has some distortion because of the sampling rate.

I was also thinking if 2000 waveforms/second is good enough. I will use it in embedded and IoT projects.

Am I missing something here? Are there other tips for buying a good digital oscilloscope?

Thanks.
 

MrChips

Joined Oct 2, 2009
27,679
100MHz BW refers to the analog input limitations. This means that you can view a 100MHz sinewave with no more than 3dB loss in amplitude. A 100MHz square wave is a different story. What will be affected is the reproduction of the rise and fall portions of the signal. Sharp edges demand higher bandwidth. You need the higher BW for faithful reproduction.
Distortion is not a result of the sampling rate once you have sufficient samples to display the waveform. The DSO will interpolate between samples.
Distortion while viewing a non-sine signal is caused by low BW.

Therefore, yes, having higher BW is useful.
The more important question is, what is the instrument being used for and what type of signals are you most likely will be examining on a DSO?
 
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