Krishna, Michael
While noise hunting for the cBRS, we noticed that our piezos were singing at a high frequencies. After further investigation, we found ~8 kHz noise on all four of our channels coming out of the PEM anti-imaging chassis whenever we assert a value to the DAC. We ended up installing some 100 Hz low pass filters just before the cBRS electronics box to fix the issue on our end.
Attached is a scope view of the noise. The signal is on channel 2 of the scope.