PicoScope 5444D MSO detailed performance specs? (ENOB / SNR / THD / SINAD / SFDR)

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eric-haber
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PicoScope 5444D MSO detailed performance specs? (ENOB / SNR / THD / SINAD / SFDR)

Post by eric-haber » Tue Jul 30, 2019 12:14 pm

[previously asked by mail, ref. SALES-33470, reposting here so everyone can benefit from the answer]

Looking at the PicoScope 5444D MSO for a test / measurement station, to replace a competitor's piece of gear whose vertical resolution (12-bit) has turned out to be insufficient for our needs.
We mostly measure one to four signals in the 20Hz - 100kHz range, sampled at 1 to 10 MS/s, at the highest resolution we can get.

A couple of spec questions to help with the purchase decision.

Q1: Did I understand correctly that vertical resolution is limited by the number of channels? i.e. with 1 channel we can get 16 bits, with 2 channels 15 bits and with 4 channels, 14 bits?

Q2: Having reviewed the 5000D series datasheet at https://www.picotech.com/download/datasheets/picoscope-5000d-series-data-sheet.pdf, I failed to find detailed performance specs beyond the "number of bits" - such as ENOB / SNR / THD / SINAD / SFDR. Number of bits of course is not necessarily a good indication of actual performance, as it only gives an upper limit which may not be reached in practice. Does a more detailed spec sheet exist somewhere?

Best Regards
Eric

Gerry
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Re: PicoScope 5444D MSO detailed performance specs? (ENOB / SNR / THD / SINAD / SFDR)

Post by Gerry » Tue Jul 30, 2019 2:32 pm

Hi Eric,

The 5000 series PicoScopes use multiple ADC's to provide increased sample rates (interleaving ADC's) or increased resolution (stacked ADC's) so for the highest sample rates and resolutions, yes they would be limited by the number of channels (actually the number of channels available is limited by the highest resolutions selected). So, for this reason, along with the fact that the noise levels are relatively high on the 5000 series in comparison to, for instance, our 4000 series PicScopes, I would say that for high resolution work (e.g. audio) the PicoScope 4262 (See here: https://www.picotech.com/oscilloscope/4262/picoscope-4262-overview) is the better choice.

If you look under the Dynamic performance section of our Specifications, you will see that SFDR is quoted as :
8 to 12-bit modes: 60 dB at 100 kHz full scale input.
14 to 16-bit modes: 70 dB at 100 kHz full scale input.

Harmonic distortion is quoted as :
8-bit mode: −60 dB at 100 kHz full scale input.
12-bit mode or higher: −70 dB at 100 kHz full scale input

and noise (on the most sensitive range, i.e. worst case) is quoted as:
8-bit mode: 120 μV RMS
12-bit mode: 110 μV RMS
14-bit mode: 100 μV RMS
15-bit mode: 85 μV RMS
16-bit mode: 70 μV RMS
which for a signal at ±10mV p-p, or 7071uV RMS, in 16-bit mode, would give a SNR value of -40dBc,
In comparison, a PicoSope 4262 on it's most sensitive range of ±10mV p-p, has 8.5uV of noise RMS or 7071uV RMS would give a SNR of -58dBc

This would give an ENOB of just under 7 for the 5000 series PicoScopes, and an ENOB of just under 10 for the PicScope 4262. However, using some of the available noise reduction methods such as Resolution Enhancement, Waveform Averaging, Filtering, etc, the noise can be significantly reduced, and taking advantage of the reduction in noise due to Process Gain in Spectrum Mode it can be effectively eliminated.

Regards,

Gerry
Gerry
Technical Specialist

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