Question

Problem 6 (15 points): The general structure of an N -bit R-2R ladder digital to analog converter (DAC) is shown below, where the voltages at each of the input pins are either 0 or 4 V (for binary "O" and "1", respectively). Assume N- 5. A stream of 5-bit unsigned integers, x[n], are applied to the input of this ladder in binary format (for example, if x13-12, which is B01100 in binary, then a2 and a3 are 4V while ao, a1 and a4 are 0 V each at sampling instance, n-3) ao a1 42 an-2 an-1 2R 2R 2R 2R 2R out 2R a) b) c) d) How many resistors do you need to build the ladder? What is the output voltage, Vout, when the input is B10100? when the input is xl 4] 17, what are the voltages at ao» a1, a2, аз and a4 ? I#x[k] changes by 1, what is the magnitude of the change in Vout? (in other words, what is the resolution of the DAC?) If the inputs are 6-bit unsigned integers, is a 5-bit DAC useless? If not, how can you still utilize this 5 bit DAC? e)

Answer 1

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