Download Sheet 2, mod

Lab 2 : Operational Amplifiers
1.1 OBJECTIVE
1. To sketch the following basic op-amp circuits and explain the operation of each:
a. Inverting amplifier
b. Non-inverting amplifier
c. Voltage follower
2. To analyze and design circuits of the type listed in items above for input & output impedances,
voltage gain and bandwidth.
3. To trouble shoot and analyze faults in the op-amp circuits.
1.2
a.
b.
c.
d.
e.
f.
HARDWARE REQUIRED
Power supply
Equipments
Resistors
Capacitors
Semiconductors
Miscellaneous
variable regulated low voltage dc source
AVO meter, CRO, DMM
1k, 4.7k, 10k, 20k, 100kΩ
IC 741 op-amp Bread
board and wires
1.3 PRE LAB QUESTIONS
1. Identify each of the op-amp configurations.
2. A non-inverting amplifier has R1 of 1kΩ and Rf of 100kΩ. Determine Vf and (Feedback voltage
and feedback fraction), if VO = 5V.
3. For the amplifier in Fig.(b) determine the following: (a) VO
(b) Vf.
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Mechatronics ME 591 Lab2 “op-amp”
4. Find the value of Rf that will produce closed-loop gain of 300 in each amplifier in Fig.(c).
5. Determine the approximate values for each of the following quantities in Fig.(d) Iin, If, Vo
6. If a signal voltage of 10mVrms is applied to each amplifier in Fig.(e), what are the output.
voltages?
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Mechatronics ME 591 Lab2 “op-amp”
1.4 EXPERIMENT
(1) Non-Inverting amplifier
1.1 Design a non-inverting amplifier for the gain of 15. Let R1=1.5kΩ. Assemble the circuit.
1.2 Feed sinusoidal input of amplitude 100mV and frequency 1 kHz.
1.3 Observe the input voltages and output voltage on a CRO. Tabulate the reading in Table 1-1.
1.4 Compare the experimental results with the theoretical values.
(2) Voltage follower
2.1
2.2
2.3
2.4
Assemble a voltage follower circuit.
Feed sinusoidal input of amplitude 100mv and frequency 1 kHz.
Observe the input and output voltages on a CRP. Tabulate the readings in Table 1-1.
Compare the experimental results with the theoretical values.
(3) Inverting amplifier
4.1
4.2
4.3
4.4
Design an inverting amplifier for the gain of 15. Let R1=1.5kΩ. Assemble the circuit.
Feed sinusoidal input of amplitude 100mv and frequency 1 kHz.
Observe the input and output voltages on a CRO. Tabulate the readings in Table 1-1.
Compare the experimental results with the theoretical values.
Table 1-1
op-amp configuration
/ circuit
Input signal
Amplitude
Frequency
Output signal
Amplitude
Frequency
Voltage gain
Designed
value
Observed
value
Non-inverting amplifier
Voltage follower
Inverting amplifier
1.5 POST LAB QUESTIONS
1. What is the relationship, if any, between the polarity of the output and input voltages in your
experimental op-amp? Refer to your data.
2. Determine the bandwidth of a non-inverting amplifier, voltage follower and inverting amplifier that
were implemented in the laboratory.
3. Determine the gain-bandwidth product of each amplifier.
4. Determine the input and output impedances of each amplifier.
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Mechatronics ME 591 Lab2 “op-amp”
5. Determine the most likely faults for each of the following symptoms in fig. 1.5-1 with a 100 mV
signal applied.
(a) no output signal
(b) Output severely clipped on both +ve & -ve swings.
6. Determine the effect on the output if the circuit in fig. has the following fault (one at a time).
(a) output pin is shorted to the inverting input
(b) R3 is open
(c) R3 is 10 kΩ instead of 910 Ω.
(d) R1 and R2 are swapped.
Fig. 1.5-1
1.6 ADVANCED PROBLEMS
1. Design a non-inverting amplifier with an appropriated closed-loop gain of 150 and a minimum
input impedance of 100MΩ.
2. Design an inverting amplifier using a 741 op-amp. The voltage gain must be 68 +5% and the input
impedance must be approximately 10 kΩ.
3. Design a non-inverting amplifier with an upper critical frequency of 10 kHz.
4. Design an inverting amplifier if a midrange voltage gain of 50 and a bandwidth of 20 kHz is
required.
5. Show the connection of 3-stage amplifiers using 741 op-amp with gains of +10, -18 and -27. Use a
270 kΩ feedback resistor for all three stages. What output voltage will result for an input of
150µV?
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Mechatronics ME 591 Lab2 “op-amp”