5000 vs 4262 noise performance

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packo
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5000 vs 4262 noise performance

Post by packo » Thu Jun 07, 2018 4:44 pm

For making an informed purchase decision, I am interested in comparing the noise performance of the 5000 series versus the 4262 when both are set to 16bit mode at the same input BW limit.

According to the specs (I target 5242D for my calculations):

5242D specified noise: 70uVrms @2mV/div@60MHz
4262 specified noise: 8,5uVrms@2mV/div@3MHz

If we bandlimit the input to 200KHz (e.g. using a filter at the input) the noise will reduce to roughly:
70*0,2/60 = 0,233uVrms for the 5242D
and to 8,5*0,2/3 = 0,567uVrms for the 4262.

Which means that for a full-scale sine wave of 20mV, using the well-known formula:

ENOB = (-20log10(6,6x0.001x Vrmsnoise / 20e-3)-1.76)/6.02

or

ENOB(5242D@2mV/div@60MHz) = 5.14 bits
ENOB(5242D@2mV/div@200kHz) = 13.37 bits
ENOB(4262@2mV/div@3MHz) = 8.19 bits
ENOB(4262@2mV/div@200kHz) = 12.09 bits

which means that the 5242D outperforms the 4262 in terms of noise performance when both have bandlimited inputs.

Are my calculations correct?

packo
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Re: 5000 vs 4262 noise performance

Post by packo » Thu Jun 07, 2018 8:54 pm

I realize that the published noise specs include both the input front end noise and the ADC noise. But because the 5000 series has a scalable ADC architecture I do not fully understand which part of the architecture contributes most to the noise figures of the specification.

Is the ADC or the front end more dominant when the 5000 series is configured at 2mV/div and 16bits? (I was thinking of connecting a filter at the input of the 5000 series to further reduce the published noise specifications.)

Martyn
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Re: 5000 vs 4262 noise performance

Post by Martyn » Mon Jun 11, 2018 6:29 am

If you can email support@picotech.com regarding the questions you are asking across different topics we will be able to give you a full answer to enable you to make an informed choice on scope and accessories.
Martyn
Technical Support Manager

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