PXI-4132 Precision Source Measure Unit (SMU), reverse high-low terminal function?

[MagnusH]

Hi,

I am considering buying the PXi-4132 SMU card from NI that can do ±100V, however after reading the documentations I am uncertain about its functionality and configurability.

In my configuration that I want to setup I need to be able to apply ±100V on each of the output Low and High terminals of the SMU. Let me clarify:

Lets say I want to configure the SMU as a voltage source and put the output high terminal at +100V and output low terminal at -100V, then at a later stage, switch this so that output high is now -100V and output low +100V, the reverse configuration that is. Is this possible with this SMU card?

If the total potential across the terminals i maximum 100V then one can expect that +50V at high terminal and -50V at low terminal is the limit, this will also be ok for my application, the important thing is that both terminals can be changed between both positive and negative potential. 

Or is output low always 0V and only the output high terminal is changeable between ±100V, I guess this might be the case due to the labels of the terminals (high and low), this however will of course not work for my application.

Do someone have some experience with this particular type of card and can clarify the functionality of it for me?

Best Regards

Magnus Hummelgård 

[RT4CY]

Hello Magnus,

I believe you are asking whether the HI and LO outputs of the 4132 can be individually controlled as if they were independent power supplies.  The way it works on the 4132 is that there are voltage and current control loops which sense the HI/LO differential voltage.  When we program 100V, we measure back the output voltage (via the control loop) and adjust the output to match 100V.  The same thing happens for -100V (i.e., the differential between HI and LO is equal to the programmed output).  

For your application, I would recommend cascading two 4132 SMUs.  By cascading the outputs of both SMUs you will essentially have one SMU ... but you can program the "HI" and "LO" independently of each other.  I hope this is helpful, let me know if anything I stated in this post is unclear.

[MagnusH]

Thanks Rod,

I think that clarifies it. 

I don't actually need fully individual control of each terminal, just to mirror each other in sign of potential. If the channels are isolated I guess I can make a simple voltage divider by a par of serial connected resistors and connect the middle section to ground and I will get a ±50V on each of the termianals, is this right?, se the sketch that I made. Of course I will only get a max potential of 100V in total with this configuration.

 

/Magnus 

[RT4CY]

Hello Magnus,

Yes you are correct.  Assuming you tie ground to the middle as shown in your diagram and measure from + to Gnd, you will see +50V.  Measuring from - to Gnd you will see -50V.