THE NON-INVERTING AMPLIFIER
The purpose of this exercise is to investigate the performance of a non-inverting
amplifier which incorporates an operational amplifier.
Equipment: Dual Power Supply, Generator, Oscilloscope, DMM, Breadboard, µA741 ,
2 Resistors
PROCEDURE
(a)
Construct a non-inverting amplifier having a voltage gain somewhere between a
lower limit of 10 and an upper limit of 20. Use a 741 operational amplifier and a
±15 V dual power supply.
Draw the circuit diagram. Note the values of resistors and expected gain
(b)
Apply a suitable input signal and measure the mid-band voltage gain. Express the
gain in dB. Draw waveforms.
(c)
Increase the amplitude of the input signal until clipping occurs at the output. Does
clipping take place at the expected levels? Draw waveform.
(d)
Attempt to measure the input impedance of the amplifier. Outline the method used
and comment on the result.
(e)
Attempt to measure the output impedance. Outline the method used and comment
on the result. How does it compare with the theoretical value?
(f)
Using the gain bandwidth product of the 741 op-amp (1 MHz) Calculate the
expected bandwidth of the amplifier.
(g)
Determine the maximum peak output voltage at which slew rate limiting would
occur at the cutoff frequency determined above. (Assume SR=0.5 V/us).
Vo (max) = SR / 2πf
In order to measure the amplifier bandwidth without slew rate distortion the level
of output signal must not be greater than Vo(max)/10. Note and Explain results.
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(h) Set the output voltage to the above level and measure the cutoff frequency. How
does it compare with the figure obtained in (f)? Draw waveform of VO at the cutoff point.
(i) Increase the amplitude of the input voltage to 5·Vo(max) and observe and record the
output voltage at the cutoff frequency. Explain the result.
(j)
Apply a 10 kHz square wave and observe output waveform. The amplitude of the
input square wave should be large enough to cause the output to reach 10 V at least.
Can you detect slew rate limiting? Measure the effective value of S. How does
it compare with the rated value? Draw waveform of VO.
(k) Connect the amplifier input terminal to ground and measure the output offset
voltage. VOFFSET=
DT 009/2
INDUSTRIAL ELECTRONICS LABORATORY