50mV peak in analoge sine output, f=10kHz

[funkymunky]

Good morning!

Yesterday I found that when I create an analoge sine ouput signal (either with a labview program or in the M&A test panel) the sine has a 50mV peak when it changes sign(+/-)

I'm using a USB-6212

labview 8.6

sample frequency: 200kS/s

sine frequency:       10kHz                     

The peak is still there for 1000Hz (stil 50mV), but I dont see it for 10Hz frequencies.

The peak amlitude does not change for Amplitudes between 1V to 10mV.

I see the same glich on AO-0 and AO-1, and it is always when the sine =zero.

Does any one know: "What this is?" and more important: What can be done about it?????

I've attached a picture of the peaks for a sine with amplitude 10mV.

Applying a filter to take out the peak would be my last resort, but that does not seem like the way to go.

Thank you so much,

Tasio

[Henrik_Volkers · Accepted solution]

That glitch (spike) is typycal for some (simple) DAC designs. A simple RC filter can help . Bonny Baker wrote an article in EDN about it and a KB article about this topic from NI is also somwhere at ni.com....

[funkymunky]

Thanx Henrik!

That helps a lot. At least for the understanding. I'm not sure if I can buy a string DAC but its either that or filtering.

And filtering is not realy an option since I would like to be able to change the frequency...

If any one else is interested: http://www.ti.com/lit/an/slyt300/slyt300.pdf and http://pages.nxtbook.com/nxtbooks/ubm/edn_20110728/offline/ubm_edn_20110728.pdf (ctr+f Bonnie Baker)

might be of interest.

So thank you very much Henrik,

may you live long and prosper:)

Cheers,

Tasio

[funkymunky]

"The glitch is most prevalent during the MSB transition, when bits are switching from 7FFFh to 8000h (for a 16 -bit DAC)" [1]

What if I keep transitions from 7FFFh to 8000h from happening? I could just change the range or give my sine an offset? 

I might see the second most significant bit change, but would not have as large a glitch.

[1]Bonnie Baker: http://www.ti.com/lit/an/slyt300/slyt300.pdf (page 6 lower part)

[Raman_is_Here]

What is the maximum value of current that the Elvis II can sink in ??? I am using function generator to produce a sine wave.plz tell me wht the max current ratings so that nuthing happens o my elvis 🙂