Sigma Delta ADC AD9261 (AD9261-10) ringing in output signal (step response)


I am using the Sigma Delta ADC AD9261-10 for the measurement of pulses (rise time approx. 50-300ns). All in all the ADC works really good on my PCB but there is ringing.

The ringing occurs before and after a step/pulse. The post-ringing is something I could understand because of the internal filter. Now my question is, can the pre-ringing also be attributed to the filter of the ADC algorithm or are there other reasons? It seems the PCB with grounding and so on is not a  issue in this case. Does anyone have experience in this field or had the same behavior/response?