to high measurement time for NI PXI 4132

[edakoto]

Hi,

I'm using 4132 to measure very small current of photo transistor device. with 25v source to the DUT it takes me more than 100ms to get an stable current reading.

How will i reduce measurement time?

tnx!

[Patrick_NI]

Hi edakoto, 

What current levels are you reading?  How are you acquiring the data in software?

One thing to try is to reduce the Aperture time of the device.  The PXI 4132 defaults to an aperture time of 16.6 ms.  You can reduce this using the Configure Aperture Time VI or function.  For more information see here:

http://zone.ni.com/reference/en-XX/help/370736F-01/ni_dc_power_supplies_help/4132_aperture/

Thanks

[edakoto]

Hi,

i've tried changing the aperture time to smaller value but the current still takes long time to stabilize before measuring nA current.

time is critical for me because i will be hooking up to an automatic test handler.

does cable have effect on my measurement? I'm currently using 2m long and  #24wire to my UUT.

[Patrick_NI]

Hi, 

What exactly is taking a long time to stabilize, the current or the time to take the measurement?  Please walk me through your procedure of how you determined that it is unstable, and how you are setting the measurement time to account for that.

The cable length does have an effect, but that effect will on the micro or nano second scale, and should not account for the high measurement time.

[Patrick_NI]

Hi edakoto, 

It looks like another user was in a similar situation as you.  Have a look at the information in this thread for further testing:

http://forums.ni.com/t5/Digital-Multimeters-DMMs-and/4132-SMU-measurement-time-is-too-high/m-p/19091...