2. The Op-Amp as the no-inverting Amplifier
Aim
Feedbackcontrol of the Non-invertingOperationalAmplifierisachievedbyapplyingasmall partof
the outputsignal back to the inverting(-) inputterminalviaaRf – R2 voltage dividernetwork,again
producingnegative feedback.If the value of the feedbackresistorRf iszero,the gainof the amplifier
exactlyequal toone (unity).If resistorR2is zerothe gain will approachinfinity,butinpractice itwill
be limitedtothe operational amplifiersopen-loopdifferential gain,(Ao).
Equipment
 Dual powersupply
 Oscilloscope
 741 Op-Amp
 Signal generator
 10k, 100k resistors
Circuit
Method
 I buildthe circuitabove usingCircuitmaker.
 I connectthe signal generatorandmonitorVinandVoutusingthe CRO.
 We use 1kHz, 100mV peak-to-peaksinewave inputsignal verifythe formula
+V
V4
0V
+V
V3
-15V
+V
V2
15V
1kHz
V1
-100m/100mV
+
U1
OPAMP5
Rf
100k
Rin
10k
A
B

3. Calculatedresults
V1=
𝑅2
𝑅2+𝑅𝑓
*Vout
V1=Vin
Voltage gainA(V)=
𝑉𝑜𝑢𝑡
𝑉𝑖𝑛
ThenA(V)=
𝑅2+𝑅𝑓
2
Transpose to give A(V)=1 +
𝑅𝑓
𝑅2
A(v)=1+
100𝑘
10𝑘
= 11
Vin=0.10v
Vout=1.10v
A(V)=
𝑉𝑜𝑢𝑡
𝑉𝑖𝑛
=
1.10𝑣
0.10𝑣
=11
Simulatedresults
Conclusion
The secondbasic configurationof anoperational amplifiercircuitisthatof a Non-inverting
OperationAmplifier.Inthisconfiguration,the inputvoltage signal,(Vin)isapplieddirectlytothe
non-inverting(+) inputterminal whichmeansthatthe outputgainof the amplifierbecomes
“positive”invalue in contrasttothe “InvertingAmplifier”circuitwe saw inthe lasttutorial whose
outputgainis negative invalue.The resultof thisisthat the outputsignal is“in-phase”withthe
inputsignal.
0.000ms 0.500ms 1.000ms 1.500ms 2.000ms 2.500ms 3.000ms 3.500ms 4.000ms 4.500ms 5.000ms
1.250 V
0.750 V
0.250 V
-0.250 V
-0.750 V
-1.250 V
A: rf_2
B: v1_1