Unusual signal pattern at the output of STM32G474 DAC3

[imalamoud]

Hello,

I am implementing a sine wave generator based on the high-speed DAC3 of the G474.

The DAC is in double-DMA mode and its conversions are triggered periodically  by a timer.
Sample and Hold is disabled.

The DAC is connected to an external pin by an OPAMP in the follower mode.

What could be the reason for the downward slope shown on the picture? It is consistent even at low conversion speeds.

Thank you for your help.

[KnarfB]

Why not using sample&hold?

From the reference manual: " In sample and hold mode, the DAC core converts data on a triggered conversion, and then holds the converted voltage on a capacitor. When not converting, the DAC cores and buffer
are completely turned off between samples and the DAC output is tri-stated, therefore
reducing the overall power consumption."

hth

KnarfB

[MasterT]

I'd check opamp first, configuring as standalone and applying external signal.

Btw, have you done dac & opamp calibration?