SMU 4140 current pulse question

[cijgr]

Hello everyone,

I am seeking any advice or help on how to maintain stable a current pulse when its frequency is increased.

The equipment:

Chassis PXIe1078

Controller PXIe 8115

SMU: PXIe 4140 (4 channels)

The problem: I am correctly generating a 7mA - 14mA current pulse up to 20Hz but when I increase the frequency to for example 100Hz, the current signal attenuates to a 10mA - 12mA pulse, and if I keep increasing the frequency the signal becomes a complete mess.

Questions: How can I manage to stabilize the current pulse to higher frequencies without signal attenuation? Am I following a correct programming strategy from the point of view of the VI's that I am using? or should I use the "Current Pulse VI" of the DC power palette for example?

The VI: please find attached the VI that generates the current pulse. Try increasing the frequency (by reducing the time parameters in the "Delay" array)  

Thanks for your kind help,

Cesar

[Henrik_Volkers]

I can't open your vi, but a more general question:

What are you driving? 

If you load is inductive you probably can't increase your current as fast as you want 😉

[cijgr]

Danke fuer deine Antowrt Henrik, (my German is terrible...)

The current is passing through a 1kOhm resistor that cannot be changed to a lower value. I've checked the SMU 4140 module specs and the voltage range is -10V to 10V and thats low considering the fixed resitor value.

I might be wrong, but I think I cannot achieve my goal with this SMU module.

Still, further ideas or advices are greatly appreciated.

Greetings from Mexico,

Cesar 

[johnsold]

Ohm's Law: 10 V/1000 ohms = 10 mA. Therefore you cannot get 14 mA.

Lynn

[cijgr]

Indeed Lynn.

Thank you.

Cesar