The ladder network has R and 2R connected as shown. The binary inputs are switches which can be connected to either Vref = 16V (logic 1) or OV (logic 0).
The output voltage Vout is generated depending on the input voltages at the switches.
Using superposition theorem, output voltage generated for more than one switch at logic 1 is addition of voltages due to the individual switches.
The voltage developed at the output of ladder network is proportional to the binary inputs. This voltage is fed to the voltage follower circuit using op-amp and Vut is obtained.
