4-bit Inverted Op Amp DAC

: Addition of digital inputs (0 or 1, where say 1 corresponds to 5 volt) give rise to analog output, which can be added with different weights considering their place in binary number. But this type of circuit has a disadvantage of requirement of large number accurate resistors for high number of bits. For example, 8 bit converter requires eight resistors ranging from some value R to 128R. R/2R ladder DAC circuit (Figure 1) eliminates this problem. Task1: Design a 4 bit R/2R ladder DAC using 741 op amp by choosing components appropriately and test the circuit. Performance of DAC is characterized byResolution, Accuracy, Linear errors, Monotonicity and settling time. What above terms mean? Output voltage of the DAC circuit is given by 𝑉௢௨௧ = − ோಷ ோ ቀ ௗభ ଶ భ + ௗమ ଶ మ + ௗయ ଶ యቁ where d1 is M.S.B and d3 is L.S.B. In the above circuit, feedback resistance RF = 2R. Output impedance of the R-2R network is always R, for any number of bits in the network. This is another advantage of the circuit as it simplifies the design of circuits which use DAC such as filtering, amplification etc.