ad9680 Triangular waves

I used ad9680 to collect data, which was configured with M=1,L=2 and F=2. When I collected triangular waves, I found that the waveform observed with ILA in fpga was distorted. The triangular wave has a frequency of 1MHZ and an amplitude of 1V. I have used an oscilloscope to check the waveform output of the signal generator, and its waveform is normal. I've also done square and sine waves, as shown below.

Hope to get your reply. Thank you

Triangular waves