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DAC7822: DAC7822 and OPA2228 setup oscillation

Part Number: DAC7822
Other Parts Discussed in Thread: OPA2822, OPA2228, , OPA810, TINA-TI

Dear all,

This thread can be considered the continuation of the following thread: e2e.ti.com/.../dac7822-offset-at-the-voltage-output

I have a board with the following schematic (see pictured). It is based in a DAC7822 and OPA2822 OA. This schematic  produces an offset of 185mV on the output. For that reason, and following recommendation of this forum, I changed the OA to OPA2228 (lower Ibias and lower GBW). Effectively the offset disappeared but a new effect has come.

In the next picture, you can see how de combination of DAC7822+OPA2822 behaves when I introduce a ramp from code 0 to code 4095. From ramp to ramp, the DAC pass through middle range code 2048 before goes to code 0. In the picture (bottom zoom view ) is possible see how the steps has good shape.

In the following picture, with the same input, you can see output waveform in the combination of DAC7822+OPA2228. The bad effect can be seen in the bottom zoom view where from step to step there are oscillations.

My guess is that the oscillation is produced because the OPA2228 has a lower GBW and the setting time is 2uS. Am I correct?

Is there any way to suppress this setup oscillation? Any OA compatible to OPA2822 so we can replace then a make actual board functional?

Thanks in advance,

Joaquin.