a) Compare the active (with OPAMP) and passive (without OPAMP) DAC circuits. What is the advantage of active DAC circuit based on? Explain.

b) With a 4-bit DAC (1011) containing an active circuit element (OPAMP), 2 binary numbers are wanted to be converted to analog signals. This binary number of logic-0 bits are represented by Vin = 0 Volts and logic-1 by Vin = 4 Volts. Draw this DAC circuit. Write the equation of the Vout output voltage and calculate the value for the given binary number.