MulitSim Simulation of A/D and D/A Converters. 1. Simulate a 4-bit R-2R Ladder Digital to Analog Converter. Use two op-amps (opamp_3T_virtual) with pos and neg swing voltages of + 20V. The second op-amp should follow the first and have equal value resistors. The second op amp will change the sign of the voltage from negative to positive. Use virtual R = 10k resistors (not rated) Use a reference voltage of 12.0 V. Complete table 1 showing the digital input code and the corresponding analog output voltage. State the resolution (K) of the 4 bit dac, and show your calculation. Resolution Calculation K = Instructors initials: Table 1. 4 bit DAC B3 B2 B1 B0 Vout[V] 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 1 1 1 1 0 0 1 1 0 1 1 1 1 0 1 1 1 1 Suggested Components: Comparator_Virtual, 74LS393D, 74LS194D (two), voltage_controlled_spdt (one for each bit), opamp_3T_virtual (two), PB_NO (electromechanical group) clock signal. 2. Modify the R-2R Ladder from question 1 such that it is an 8-bit Ladder. This will be used in the Analog to Digital converter. You will need to automate the switched by using voltage_controlled_spdt components, 1 for each bit. These will be controlled by the counter outputs and direct the current of the R-2R ladder into the op amp or to ground. 3. Simulate an 8-bit ramp ADC using a clock, counter and R-2R ladder. Compute the digital codes for the voltages indicated in table 2. (note the last column requires you to complete assignment 5 below). Show the hex code for each voltage along with its binary code. 4. Calculate the resolution for the Counter Ramp ADC. Using the hex code generated by the ADC, convert it to binary and show how close the analog voltage generated by the digital code is to the Vin voltage. Table 2. ADC Vin [V] Counter-Ramp ADC ADC Integrated Circuit 2.85 3.42 4,76 6.55 8.24 10.72 Instructors initials: Be sure you instructor sees and initials the working simulations for questions 1 and 3. Suggested Components: ADC (ADC_DAC Group), SPDT (two), NOT (misc digital) 74HC273DW_6V, hex_dcd displays (two), VCC for vref (12V), VDD = 5V for switched high state, ground = 0 for switched low state, DC_Power for the Vin voltages (see table 2), digital ground (connected to nothing, just on your model). 5. Create a new model that utilizes the ADC component (from the ADC_DAC Group), a data register (74HC273DW_6V 2 hex_DCD displays VCC = 12V for Vref, VDD = 5V for the switches DC_Power for the analog voltage input (Vin) a ground and a digital ground (not hooked to anything). Complete the last problem in table 2. 6. Calculate the resolution for the ADC component constructed in step 5. Using the hex code generated by the ADC, convert it to binary and show how close the analog voltage generated by the digital code is to the Vin voltage. 7. Can you explain the difference between the voltages corresponding to questions 4 and 6? (Hint: think about the fact that one of the voltages from questions 4 and 6 is higher than Vin and one is lower. Relate this to the different techniques discussed in lecture).