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Pulse generator.

Posted: February 6th, 2014, 1:06 am
by Enrique

I did not find the proper place to write this question.

I need to produce a pulse of current in the range of micro second (Submicrosecond would be perfect), with rising time in the range of nanosecond. My load resistance is about 200 ohms. The current should be in the range of 100mA.

Do you have any tool capable of performing such a pulse?

Is the 2520 the proper one?


Re: Pulse generator.

Posted: February 7th, 2014, 7:29 am
by Norbert W
The model 2520 is indeed a current pulser which can deliver submicrosecond (500 ns) pulse(s). You probably may want to check for
accuracies / example rise times / dury cycle &c. in the instruments datasheet to see it generally fits your needs.
But it is also capable of several measurement channels - one channel for voltage on the DUT and 2 further
current input channels intended for use with too photodetectors (the whole product primary application is for laser diode
I would recommend you contact your local Keithley representative to discuss your application in more depth, specifically if
you have any measurement needs the unit could cover for you.

Re: Pulse generator.

Posted: February 8th, 2014, 12:02 am
by Enrique
Thanks for the answer. I just need to apply individual pulse of current. In my particular case the raising time is quite important.

Considering the specifications it seems the proper tool for my application.

I just have another question.

I have work with different Keithley instrument. For instance, The 6221A is capable to perform delta pulses of current in the microsecond scale, but only in the delta mode which only works with the nanovoltimeter 2182. The custom sweep only prudes "deltas" in the milisecond scale.

Since I only need an individual pulse. Is it capable the 2520 to perform custom sweeps with three out put currents 0, 100mA, 0 in the submicrosecond scale or I have to use a pulse mode?
Do I need any supplementary device to activate the pulse mode in the 2520?



Re: Pulse generator.

Posted: February 9th, 2014, 4:10 am
by Enrique
I have a couple of questions more.

I could not find in the 2520 manual the minimum time between two voltage measurements, Could you tell me this parameter?

Would it be possible with the 2520 take, for instance 20 voltage measurements and trigger right after the measurement 10 a pulse? or define 20 voltage measurements and establish some delay after which the pulse has to be apply?


Re: Pulse generator.

Posted: February 11th, 2014, 1:52 am
by Norbert W
Let me first comment on the 6221 AC and DC current source:
Using the sweep mode will give you 1 ms time resolution; if you go for the WAVE functionality
you can use its 100 kHz arbitrary mode to speed up. Of course setup what you need will be quite different then.
For generating a single pulse you can configure duration to output a single cycle.

Here some comments on the 2520:
It gives you nice pulses but takes some time (ms) between pulses if you are going to take measurements. This stems from
the fact the DSP based measurements are done on 3 A/D converters every 100 ns - in single pulse mode you can
use trace:data? to get these individual readings. For several pulses configured you only get a computed measurement
for each pulse where a DSP / microproc. communication is involved.
... I just saw that I overlooked you mentioning 200 Ohms / 100 mA in your first eMail. This cannot be done by a 2520 as
it is limited to 10 V. So please try your 6221 as described above.

Re: Pulse generator.

Posted: May 6th, 2020, 2:29 pm
by John Zelada
I had a similar question, but thanks to the answers I think I have resolved my question :D :D