EE-3010 Lab # 5 Simulation of Operational Amplifier Circuits

Transcription

1 EE-3010 Lab # 5 Simulation of Operational Amplifier Circuits Objectives Investigation of amplifier circuits containing operational amplifiers. (Note: This is a two-part lab and may be done in two consecutive lab sessions. The lab report will be worth 20 points.) Pre Lab - 1 Bring a 3.5 diskette to lab. You will need it to save your files. Examine the circuit of Figure 1. Identify the type of amplifier circuit and determine expected values for all meters shown in Figure 1 based on potentiometer and switch values. Enter these values in the first row of Table 1 in the data sheet. Examine the circuit of Figure 2. Identify the type of amplifier circuit and determine expected values for all meters shown in Figure 2 based on potentiometer and switch values. Enter these values in the first row of Table 1 in the data sheet. Pre Lab - 2 Bring a 3.5 diskette to lab. You will need it to save your files. Examine the circuit of Figure 3. Select values for the resistors so that there will be a gain magnification of -2 for the sum of the three input voltages. Come up with several test values for the inputs and output. Examine the circuit of Figure 4. Determine what you would expect for the output voltage.for this circuit. Also calculate the AC current through RF, RL, and the output of the op-amp. Solve Problem in the textbook. You will use these theoretical calculations in evaluating results from lab. Components Used Electronics Workbench Software for the PC Introduction 1. First, you should learn the construction and simulation of a circuit with Electronics Workbench software. 2. Circuits are constructed in the Circuit Window by dragging components from the Parts Bin Toolbar. You may rotate components by right clicking the Rotate or flip commands. You may change the properties of a component by double clicking the component and entering new data in the dialog box. 3. Components are wired to form a circuit by moving the cursor to the terminal of a component. Click and drag to connect to another component terminal or circuit path. Connectors may be utilized to connect multiple circuit paths to a node. 4. Save all completed circuits as a file to your diskette for the next time you come to lab. This circuit can be printed to the network printer. 5. Also copy the circuit schematic and paste the bitmap image to a blank word document. You can now include it with your lab report. I suggest you do this in lab as your circuit file will not open with the Demo version of Electronics Workbench. 6. Simulation is performed for the wired circuit by pressing 1 of the power switch. Page 1

2 Part A: Inverting Amplifier 1. Open the sample circuit provided in lab with file name Fig1.ewb. 2. Turn on the circuit and enter meter values of this circuit in row 2 of Table 1 on the data sheet. Examine these values and compare with what you calculated from prelab. 3. Change input polarity (by pressing the space bar). Enter meter values of this circuit in row 3 of Table 1 on the data sheet. Does this agree with what you would expect? 4. Set the input to 0 V (input pot P to 0%) and observe all voltages and currents. Enter meter values of this circuit in row 4 of Table 1 on the data sheet. Does this agree with what you would expect? 5. Set the input to a small value (input pot P to 5%), polarity positive. Enter meter values of this circuit in row 5 of Table 1 on the data sheet. 6. Select a new value of gain using the G or SHIFT-G key to vary the feedback resistance. Complete all rows of Table 1 on the data sheet with the appropriate Gain, Input, and Polarity. What happens when the predicted output exceeds 20 Volts? Explain. Calculate the Voltage Gain A V, Current Gain A I, and Power Gain G Power with the 'G' potentiometer = 10%, 'P' potentiometer = 20%, and Polarity switch =. Figure 1 Page 2

3 Part B: Non-Inverting Amplifier 1. Construct the circuit shown in Figure 2 using electronics workbench. Note that all voltages and current will be AC so set the meters to the AC mode. 2. Turn on the circuit and examine the meter values and Oscilloscope outputs. Does this agree with what you would expect? 3. Set the input to 0 V (input pot P to 100%) and examine the meter values and Oscilloscope outputs. Does this agree with what you would expect? 4. Select a new value of gain using the G or SHIFT-G key to vary the feedback resistance. 5. Enter meter values in Table 2 for a wide range of Input and Gain settings. Select one value where the expected output exceeds 20V. Examine the oscilloscope display as you change the input and gain and describe any unusual results. What happens when the output peak exceeds 20 Volts? Explain. Figure 2 Page 3

4 Part C: Summing Amplifier 1. Create the circuit shown in Figure 3 using an Op Amp. Select values for the resistors so that there will be a gain magnification of -2 for the sum of the three input voltages. 2. Turn on the circuit. Examine and record the meter values. Examine the oscilloscope display. Does this agree with what you would expect? 3. Try different values for the resistors. Examine the meter values and Oscilloscope display. Does this agree with what you would expect? What happens when the output peak exceeds 20 Volts? Explain. Figure 3 Page 4

5 Part D: Differential Amplifier 1. Create the circuit described in Figure 4 using Electronics Workbench. Note the load resistor R L = 100Ω and a frequency of 100 Hz. Connect the oscilloscope probes to vs1 and vs2. Place meters in the circuit to measure the current through R L and voltage drop across R L. 2. Turn on the circuit. Examine and record the meter values and Oscilloscope display. Does this agree with what you would expect? Is the circuit voltage inputs in RMS, V p, or V p-p? 3. Move Channel 2 of the Oscilloscope to the output. Turn on the circuit. Examine and record the Oscilloscope display. Does this agree with what you would expect? 4. Try different values for R L. Examine the meter values and Oscilloscope outputs. Does this agree with what you would expect? Figure 4: Differential Amplifier Page 5

6 Table 1 Data Sheet Polarity P Input G Gain I (in) V (in) I (invert'g) I (Feedback) V (diff) V (out) I (non-inv'g) Prelab + 20% 10% + 20% 10% 20% 10% 0% 10% + 5% 10% + 40% 5% + 40% 10% + 40% 15% 40% 15% + 40% 20% + 50% 20% Table 2 P Input G Gain I (in) V (in) I (invert'g) I (Feedback) V (diff) V (out) Prelab 100% 10% 100% 10% 0% 10% Your Name Lab Instructor Date Page 6