Name and student ID:_______________________
Eng3N03 ELECTRONICS LABORATORY
OPERATIONAL AMPLIFIER
Please write the answers, in the spaces provided on this sheet, to the following questions.
NOTE: All numeric values in any of your answers should include units, e.g. Volts, seconds, etc.
OBJECTIVES: To gain experience in the use of basic electronic instruments. To investigate some basic
operational amplifier (OA) characteristics and application circuits.
EQUIPMENT: Digital multimeter (DMM); function generator (FG); ±15V DC supply; oscilloscope
(scope); circuit board; LF411 operational amplifier (OA); 10 nF capacitor(x1); resistors(±1%):10 kΩ (x3).
THEORY: Refer to your textbook and class notes and the LF411C data sheets.
PROCEDURE:
Caution: Switch off the power supply and reduce FG signal amplitudes when making changes to your
circuits. Switch on the power supply first, then increase signal levels when switching on.
Reverse the order when switching off.
In the following OA circuits:
Use short neat wires and component leads to make interconnections (a pair of needle-nose pliers will prove
useful). Use the FG to supply the input signal vI.
Display voltage transfer characteristics on the scope using its XY display format facility (dc-coupled).
Use the FG controls and the scope cursors to measure selected critical points and incremental slopes
("voltage-gains") of the transfer characteristics.
package pin diagram (top view)
L1. Connect the OA circuit shown. R = 10 kΩ. Display vO versus vI, and measure the voltage-gain Av.
Q1. Av = __________
ENG3N03 Lab 2
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L2. Connect the OA circuit shown. R = 10 kΩ. Display vO versus vI, and measure the voltage-gain Av.
Q2. Av = __________
L3. Connect the OA circuit shown. R = 10 kΩ. Display vO versus vI, and measure the voltage-gain Av.
Q3. Av = __________
L4. Connect the OA circuit shown. R = 10 kΩ, C = 10 nF. With vI set as a square-wave of suitable
frequency and amplitude, show that the circuit functions as a low-pass active filter. Measure the 10%-to90% rise-time "tR" of the filter.
Q4. tR = ______________
Q5. Use the relation tR*fH = 0.35 to determine the 3dB cutoff frequency "fH" of the low-pass filter.
fH = ______________
ENG3N03 Lab 2
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L5. Connect the OA circuit shown on next page. R = 10 kΩ, and C = 10 nF. Show that with vI a squarewave (zero dc offset) of suitable frequency and 1 Volt peak-to-peak voltage, the circuit functions as an
inverting integrator.
Q6. Keeping other vI signal attributes as above, over what square-wave frequency range does the circuit
function as a "reasonably accurate" integrator?
PREPARATION:
ENG3N03 Lab 2
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