AD5066 noise model

Question

My (simple) noise model of the AD5066 is an 8k resistor's thermal noise plus the reference buffer's thermal noise (~60nV/rt-hz ??) multiplied by code/(full-scale code). Does that sound reasonable?

ADIApproved · Accepted Answer

Noise from the reference will couple to the output so the plot would include reference noise. 
 The AD55541A or AD5542A have better noise numbers but you will need to add an amplifier on the output.)

ADIApproved · Answer

That is a reasonable approximation. The reference buffer noise may be a bit better. The plot below is from the AD5062 which uses a very similar buffer to the AD5066. A value of 25-30nV/rtHz may be more accurate but 60 is a good value to keep some safety margin.