Pulsed two channel operation of Keithley 2602B

Hardware Issues
1

Hi,

I am running a Keithley 2602B SMU with sweepme using both channels. Channel B is used for supplying an OLED and Channel A to read photocurrent of an photodiode.

When the OLED is supplied with a regular sweep, i.e start from 0V until say 3V with steps of 0.05V, I have no problem recording the photocurrent from channel A.

However, when the OLED is run with pulsed mode, the photocurrent from channel A is orders of magnitude smaller. This leads me to believe that the photocurrent is measured either during the rise or fall period of the OLED driving pulse. I am not sure if this is the case, but in any case I was not able to solve it by tuning the “width in s”, “off time in s” or applying a delay/hold between the two actions within the sequencer.

Is there a way to synchronize the two channels in SweepMe such that the channel B can be driven in pulsed mode, with the channel A taking a measurement at a given defined point of each pulse?

Screenshot of the sequencer (without any delay/hold modules inserted)

Capture
Capture936×896 18.7 KB

Best,
Aron Dahlberg

1 Like
2

Hi Aron,

I have used pulse mode of the Keithley 2600 dual channel SMUs myself and I think it is as you expect. Reading the photodiode in DC mode is not in sync with the pulse. This could be also because the SMU integrates in DC mode over some time and the pulse makes only a port of this integration time. But of course only Keithley can answer this fully.

My recommendation would be to put both channels into pulse mode. The driver is written in a way that both channels then perform a synchronized Dual pulse measurement. The pulses are then fired at the same time and one of the channels encapsulates the other one but I’m not sure anymore in which direction this works.

If your photodiode is fast enough which is typically the case at e.g. 0V, you should be able to measure the correct current, while pulsing the OLED.

Can you test this?

Thanks and best,
Axel