Offset and Thermal Drift

Q

I have selected the AD9257 for my application and need to better characterize
the thermal drift. The datasheet specifies an offset drift of +/- 2ppm/°C.
Could you please let me what unit the ppm are referring to ? Is it full scale
input voltage (2V)?

A

For the offset it is full scale range, or 2Vp-p.
Offset drift = (drift coefficient %FSR/⁰C) * DT = ±2PPM %FSR * DT = ±2/1E6 *2
*DT = ±4uV* DT, or ±4uV /⁰C

We did not specify a gain drift coefficient on this device, but we do
guarantee all channels gain error and channel to channel matching over
temperature.