Thanks for all replies.
I think I should explain the situation in more detail, namely, why I need reference voltages from 0.807 to 0.969V with 16 taps @ 0.0108V steps. Perhaps by explaining the big picture, it might be more helpful.
It is because I am using it in non-inverting amplifier configuration to boost the various inputs to 1.5V.
My input voltage will vary from 0.807V to 0.969V in 0.0108V steps and I am trying to produce Vout=1.5V based on Vin.
So to get the right gain for Vout=1.5V, I would need the following resistor taps along R1+R2 ladder:
Vin=0.807V. This requires R1=0.538*(R1+R2)
:
Vin=0.969V requires R1=0.646*(R1+R2)
These Vin voltages come from a resistor ladder inside a bandgap reference generator cell, and I will select them via analog mux. Therefore since the Vin is known and selectable, I simply use a second analog mux to select the tap along R1+R2 to feedback to the 1.8V/0V supply OTA so that the right gain is selected to obtain Vout=A*Vin=1.5V.
So the real task isn't to generate these 0.807V to 0.969V (in 0.0108V steps) per se.
Rather these are V- voltages I need to gain up to 1.5V. I am using an OTA in non-inverting configuration with variable feedback gain to do it as shown above.
I only have 1.8V supply. And I want to make the Iload on the OTA to be 2uA so I chose R1+R2=750k,
I did look into R2-R DAC but based on my actual situation, not sure that works.
Anyway if this additional detail is helpful and anyone has any further ideas, I really appreciate it!
If not then, I likely will just go with the Runit= (R1+R2)/128 and just find the taps closest to what I need to get close to Vout=1.5V.