# Operational Amplifier Internal Circuit – 1

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This set of Signals & Systems Multiple Choice Questions & Answers (MCQs) focuses on “Operational Amplifier Internal Circuit – 1″.

1. The purpose of level shifter in Op-amp internal circuit is to
a) Adjust DC voltage
b) Increase impedance
c) Provide high gain
d) Decrease input resistance

2. How a symmetrical swing is obtained at the output of Op-amp
a) Providing amplifier with negative supply voltage
b) Providing amplifier with positive voltage
c) Providing amplifier with positive& negative voltage
d) None of the mentioned

3. Which is not the internal circuit of operational amplifier?
a) Differential amplifier
b) Level translator
c) Output driver
d) Clamper

4. What is the purpose of differential amplifier stage in internal circuit of Op-amp?
a) Low gain to differential mode signal
b) Cancel difference mode signal
c) Low gain to common mode signal
d) Cancel common mode signal

5. What will be the emitter current in a differential amplifier, where both the transistor are biased and matched? (Assume current to be IQ)
a) IE = IQ/2
b) IE = IQ
c) IE = (IQ)2/2
d) IE = (IQ)2

6. At what condition differential amplifier function as a switch
a) 4VT < Vd < -4VT
b) -2VT ≤ Vd ≤ 2VT
c) 0 ≤ Vd < -4VT
d) 0 ≤ Vd ≤ 2VT

7. Which of the following is not preferred for input stage of Op-amp?
a) Dual Input Balanced Output
b) Differential Input Single ended Output
c) Cascaded DC amplifier
d) Single Input Differential Output

8. From the circuit, determine the output voltage (Assume αF=1)

a) VO1=3.9v , VO2=12v
b) VO1=12v , VO2=3.9v
c) VO1=12v , VO2=0v
d) VO1=3.9v , VO2=-3.9v

9. For Vd &gtl ±4VT, the function of differential amplifier will be
a) Switch
b) Limiter
c) Automatic gain control
d) Linear Amplifier

10. Find collector current IC2, given input voltages are V1=2.078v & V2=2.06v and total current IQ=2.4mA. (Assume α=1)

a) 0.8mA
b) 1.6mA
c) 0.08mA
d) 0.16mA

11. Change in value of common mode input signal in differential pair amplifier make
a) Change in voltage across collector
b) Slight change in collector voltage
c) Collector voltage decreases to zero
d) None of the mentioned

12. A differential amplifier has a transistor with β0= 100, is biased at ICQ = 0.48mA. Determine the value of CMRR and ACM, if RE =7.89kΩ and RC = 5kΩ.
a) 49.54 db
b) 49.65 d
c) 49.77 db
d) 49.60 db

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