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PXIe-4163 current_limit_autorange seems doesn't work for low level current

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Hi guys,

these days i was doing some MOSFET idVg curves sweeping using PXIe-4163, as we know, for NMOS, when Vg is about 0 volt, id is very small, saying maybe 1nA or below, it turns out to several mA when Vg gets larger and larger. So I choose current_limit_autorange to switch ranges in measuring.
I found that the current resolution is not as low as my expect. When I use the fixed current_limit_range(set to 100e-9A), I got several hundred pA to several nA, but 10e-7A for current_limit_autorange.

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Solution
Accepted by topic author Onezhenji

FYI - auto-ranging is not a hardware feature but a driver feature. Enabling Auto-Ranging will let the driver choose the current range to follow the current limit setting.

 

You need to use an advanced SMU targetted for device testing like PXIe-4137 that uses hardware-level auto-ranging.

 

 

Santhosh
Soliton Technologies

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I do find a parameter called "autorange" in python's API of nidcpower, it seems that PXIe 4163 doesn't support this parameter.
So, 4163 can't satisfy my measurement requirements, right?

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Is there any way I can use PXIe 4163 to achieve my measure requirements in my topic?

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Yes, you can implement auto-ranging in software.

 

For every measurement,

  • Make a measurement at a higher range
  • Check measurement against the list of available ranges
  • Choose a range that suits the measurement value
  • Re-measure at the new smaller range
  • After the measurement is done, go back to the larger range
Santhosh
Soliton Technologies

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Well, it seems that I can not use sequence mode.

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Solution
Accepted by topic author Onezhenji

Nope, software-level auto-ranging cannot work with sequence mode as the selection of the best range happens in the application and not on hardware.

Santhosh
Soliton Technologies

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I updated nidcpower to the 2022 Q4 version, now PXIe-4163 supports auto-range. Thank u.

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@Onezhenji wrote:

I updated nidcpower to the 2022 Q4 version, now PXIe-4163 supports auto-range. Thank u.


Good to know that the latest driver updates the SMU firmware to support hardware level auto-ranging

Santhosh
Soliton Technologies

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