Download With reference to an ideal operational amplifier (op

EMT212 – ANALOGUE ELECTRONIC II
Tutorial 2 Sem. II 2010/2011
QUESTIONS
1. Calculate the output voltage for the circuit of Figure 1 with inputs of V1 = 40mV rms and
V2 = 20mV rms.
Figure 1
2.
Based on Figure 2, given the input voltage are V1= 0.2V, V2= - 0.5V and V3= 0.8V,
and the value of resistors are R1= 33kΩ, R2 = 22kΩ, R3= 12kΩ and Rf = 330 kΩ.
(i)
Calculate the output voltage, Vo of the circuit.
(ii)
Calculate the output voltage, Vo if R2 opens and the value of Rf = 400 kΩ.
Figure 2
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EMT212 – ANALOGUE ELECTRONIC II
Tutorial 2 Sem. II 2010/2011
3. A simple differentiator circuit is able to produce 10Vp-p square wave with frequency of 1
kHz when the input is applied with 12V p-p triangular wave. The differentiator circuit is an
inverting configuration and capacitor is set to 22µF.
(Hint: positive going ramp input will produce negative output)
4.
(a)
Sketch a simple differentiator circuit.
(b)
Calculate the value of resistor, R
a)
b)
c)
Design the circuit in Figure 3(a) so that the closed-loop voltage gain Av is 100
and the input resistance Ri is 1 M. Assume the op-amp A is ideal.
Determine the input resistance Ri and calculate the closed-loop voltage gain
Av of the inverting amplifier in Figure 3(b). Assume the op-amp A is ideal.
What can you observe in both circuits in (a) and (b)?
RF
R1
-
vi
A
vo
+
Figure 3(a)
R2
R4
1 M
1 M
R3
R1
vi
10.2 k
-
1 M
A
+
vo
Figure 3(b)
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EMT212 – ANALOGUE ELECTRONIC II
Tutorial 2 Sem. II 2010/2011
5.
A in the circuit of Figure 4 is an ideal op-amp.
a)
Derive an expression for the closed-loop voltage gain Av where;
Av 
b)
vO
vI
Based on the expression derived in (a), describe how you can turn the circuit
into a voltage follower and hence illustrate your answer in the form of a circuit
diagram.
R2
+
vI
A
~
vO
-
RF
R1
Figure 4
6.
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(a)
Define an operational amplifier (op-amp)
(b)
Gives 3 characteristics of ideal op-amp and practical op-amp
c)
What is the range of the output voltage in the circuit of Figure 5 if the input
can vary from 0.1 to 0.5V?
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EMT212 – ANALOGUE ELECTRONIC II
Tutorial 2 Sem. II 2010/2011
7.
a) List down 2 applications of operational amplifier
b) The figure below shows the connection of Op-amp circuit that consists of different
types of amplifier.
i)
List down the types of amplifier that consists in the circuit
ii)
Find the value of V2 and V3
200 kΩ
20 kΩ
V2
V1 = 0.2V
V3
200 kΩ
10kΩ
Figure 6
8.(a) Sketch the circuit that shows the use of TWO (2) buffer amplifiers to provide
two output signals
(b) The input waveform of an integrator circuit is a square wave of ±4.5 V. Given the
values of input resistor, R = 45 kΩ and feedback capacitor, C = 0.04 µF:
i.
Sketch and label the circuit.
ii.
Calculate the rate of change of the output voltage in response to the step input
voltage. The output voltage is initially zero.
iii.
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Sketch the resulting voltage waveform.
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EMT212 – ANALOGUE ELECTRONIC II
Tutorial 2 Sem. II 2010/2011
i.
Briefly explain positive and negative feedback.
ii.
Derive the closed-loop gain, Avf = Vo/Vi. Determine feedback transfer function, ß if
Avf = 30.
Vi
+
-
V
A1=
300
A2=
30
Vo
Vfb
ß
iii.
Let Av = 5 x 103 V/V, ß = 0.008 V/V, Ri = 10 kΩ and Ro = 1 kΩ. Determine the ideal
values of Avf = Vo/Vi, Rif and Rof. Assume the circuit is ideal series-shunt circuit.
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