DAC5311: DAC output ringing

Hello,

To be clear, you are observing some excessive small-signal settling time or is the ringing actually permanent (i.e. oscillation)?

Would it be possible for you to share an oscilloscope capture of the ringing?

As far as solutions go I have experimented with some circuits in the past resembling tank circuits to perform "output pin stability compensation" since we don't have access to the DAC output buffer feedback loop, but the simplest approach would be adding some series or parallel load resistance. As the PDS indicates stability for 1000pF loads with 2kOhm parallel load impedance.

We did try inserting resistor of 2K up to 10K in series and parallel but no impact

I suppose the second image is just a zoomed in version of the first? This doesn't really look like oscillation to me as much as some specific periodic noise source somewhere else in the system. If you remove the capacitive load does this artifact remain?

Yes you are correct both pictures are same measurements.
If I remove capacitive load it does go away.

Hello,

Thank you for your patience over the US Holiday.

Could you share a schematic and point out exactly where the measurement is being made? As I said this does not quite look like oscillation to me unless there is some aliasing or something coming from the measurement scheme you are using. Looks like some LabVIEW VI. Would it be possible to get the same captures from an oscilloscope with no bandwidth limitation?

I am afraid I cannot share schematic. But to clarify I am measuring the voltage at DAC output pin. Attached is the screen shot from oscilloscope.Yellow is the DAC output.

Hello,

What is the green signal trace which seems to be coincident with the DAC output disturbance? Were code changes applied to the DAC explaining the step responses?

Kevin,

Green is the capacitor charging discharging which is load in our case. Yes disturbance happen only during that time. And we want to stabilize DAC output during that time.

Any recommendations ?

Deepali

Deepali,

I am still trying to completely understand the situation since there is no schematic.

What causes the DAC output voltage step up and step down in the oscilloscope capture? Is that the DAC output being connected to the load or is it the DAC input code changing?

The cap being charged or discharged I guess is triggered by some external switches connecting the capacitive load?

If the issue with sharing the schematic is on account of the public forum we can take the discussion to email if you'd prefer.

Kevin,

Can we take this discussion offline ? Please your contact details.

Yes please