LINEAR APPLICATIONS OF OPERATIONAL AMPLIFIERS

Transcription

1 LINEAR APPLICATIONS OF OPERATIONAL AMPLIFIERS OBJECTIVE The purpose of the experiment is to examine the linear applications of an operational amplifier. The applications that are designed and analyzed include summing amplifier, difference amplifier, integrator and differentiator. EQUIPMENT REQUIRED 741 Op-amp Resistors (designed values), ¼ W 0-30 V, 1A dc dual regulated power supply 30 MHz Oscilloscope 3 MHz Function Generator Digital Multimeter Breadboard THEORY Op-amp is used as the building blocks of linear and non-linear analog systems. FORMULA In linear circuit, the output signal varies with the input signal in a linear manner. Summing amplifier or adder is a circuit whose output is the sum of several input signals. Summing amplifier can be realized using inverting and non-inverting configurations of op-amp. Differentiator circuit performs the mathematical operation of differentiation, that is output is the derivative of the input waveform. Integrator output is time constant times the integral of the input. Summing amplifier, ( ) Difference amplifier, FURTHER READING 1. Ramakand A. Gayakwad, Op-amps and linear integrated circuits, PHI learning, R.M.Marston, Op-amp Circuits Manual, Newnes, Robert Diffenderfer, Electronic Devices: Systems & Applications, Cengage Learning, 2005 CIRCUIT DIAGRAM Figure 1. Summing amplifier Figure 2. Difference Amplifier 34

2 Figure 3. Differentiator Figure 4. Integrator DESIGN Summing Amplifier (Adder) ( ) Difference Amplifier (Subtractor) Differentiator Let the highest frequency to be differentiated be 1 khz. Select = = 1 khz Let C 1 = 0.01 μf, Choose = 10 = 10 khz. Also, Choose such that, Integrator Choose equal to the period of the signal to be integrated. Select f =500Hz and C f = 0.01μF. Select PRACTICE PROCEDURE Summing Amplifier 1. Construct the circuit as per the diagram shown in Figure Apply 2Vp-p, 1 khz and 1Vp-p, 1 khz sinusoidal input to inverting and non-inverting terminals respectively. 3. Observe the input and output waveforms simultaneously. 4. Note the phase of the output with respect to input. Repeat the above steps for any unequal input voltages and dc voltages. 35

3 Difference Amplifier 1. Construct the circuit as per the diagram shown in Figure Apply 1Vp-p, 1 khz sinusoidal input. 3. Observe the input and output waveforms simultaneously. 4. Note the phase of the output with respect to input. Repeat the above steps for any unequal input voltages and dc voltages. Differentiator 1. Construct the circuit as per the diagram shown in Figure Apply 4 Vp-p, 1 khz sinusoidal input. 3. Observe the input and output waveforms simultaneously 4. Observe and record the peak value and phase angle of output with respect to input. 5. Increasing the frequency of the input signal and find the maximum frequency at which the circuit performs differentiation. Compare it with the calculated value of frequency. Integrator 1. Construct the circuit as per the diagram shown in Figure Apply 4 Vp-p, 500 Hz sinusoidal input. 3. Observe the input and output waveforms simultaneously 4. Observe and record the peak value and phase angle of output with respect to input. 5. Increasing the frequency of the input signal and find the maximum frequency at which the circuit performs differentiation. Compare it with the calculated value of frequency. PRELAB 1. Design and simulate an adder circuit shown in figure1 using Spice tool. Analyze the circuit and comment on the results obtained. 2. Design and simulate an subtractor circuit shown in figure2 using Spice tool. Analyze the circuit and comment on the results obtained. 36

4 3. Design and simulate an adder-subtractor circuit using 741 op-amp, so that the output of the circuit is. 4. Design and simulate a differentiator shown in figure3. Choose the signal frequency of 1kHz. Comment on the results obtained for different waveforms (Sine, Square, triangular). 5. Design and simulate an integrator shown in figure4. Choose the signal frequency of 500Hz. 37

5 Exp. No.: Date: OBJECTIVE LINEAR APPLICATIONS OF OPERATIONAL AMPLIFIERS OBSERVATION Summing Amplifier Design Circuit Diagram Table 1. Summing Amplifier Input Voltage V 1 volts Input Voltage V 2 volts Output voltage, V 0 p-p volts Calculated value V 0 Volts Inference 38

6 Difference Amplifier Design Circuit Diagram Table 2. Difference Amplifier / Subtractor Input Voltage Input Voltage V 1 volts V 2 volts Output voltage, V 0 p-p volts Calculated value V 0 Volts Inference Differentiator Design 39

7 Circuit Diagram Waveforms 40

8 Inference Integrator Design Circuit Diagram 41

9 Waveforms Inference 42

10 UNDERSTANDING & LEARNING 43

11 RESULTS AND CONCLUSION Prepared by: Name: Reg. No.: Actual Date of Experiment:. ASSESSMENT Date of Performance:.. Report Submission Date: Submission Delay:... Student Task Max. Marks Graded Marks Pre-lab Preparation 20 Inference 10 Results & Discussion 10 Signature Post-lab / Viva-voce 10 Total 50 44