This power point explains about Inverted R-2R Ladder Digital to Analog Converter

1. INVERTED R-2R
LADDER DAC

2. Why we use inverted r-2r ladder DAC?
 Current flowing in weighted register DAC varying.
 It causes large power dissipation.
 It produces heating and causes non linearity in current flowing through
resistors.
 To overcome these disadvantage we use inverted r-2r ladder DAC.

3. Circuit Diagram

4. Working
 MSB and LSB are interchanged.
 Binary input datas are connected to switch either to ground or to the inverting input
terminal of the op-amp which is at the virtual ground.
 0 - switch connected to ground.
 1 - switch connected to virtual ground.
 The current flowing through resistors constant.
 In each node,current dvides equally.
 Because the resistance value is equal in botha right and left side of each node.
 Thus the constant current implies constant voltage across each node.

5. To find Io :

7. THANK YOU