Hi

For the following D/A converter

what is the value of Rf which makes the output 8 volt if the all inputs are High ??

Thank you

 

Calculate the summed currents through the R/2R ladder. Calculate Rf to give 8 volts out for that level of current into the summing junction.

 

Hello,

You can also take a look at this page of the eBook:
http://www.allaboutcircuits.com/vol_4/chpt_13/2.html

Greetings,
Bertus