After modifying the CM board, see alog 47294, the CTRL readout has become significantly better, whereas the ERR readback has gotten a lot worse. However, the CTRL still has extra noise below 100Hz.
The slow readback was already good, but may have gotten a little better around 20-30Hz.
Compare against alog 47130.
Here we look at the slew rate at the AA board input with full sampling rate. At the input of the AA board there are 2 AD8622 which have a slew rate limit of 0.48V/us. Integrating the slew rate we get 0.3V/us, but only half of this voltage goes to each OpAmp. So, we use up about a third of the slew rate limit with the signal below 30kHz. The RMS voltage is about 2V, or 1V per OpAmp, and not limiting by itself.
The full spectrum was measured by Craig in alog 46635.
This work is associated with IIET ticket 12419
Full bandwidth spectrum.