# Analog Circuits (Test 2)

## Gate Exam : Ec Electronics And Communication Engineering

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Q.1
In the Digital-to-Analog converter circuit shown in the figure below, VR = 1V and R = 1kΩ The voltage V  is
A. −0.781 V
B. −1.562 V
C. −3.125 V
D. −6.250 V
Explaination / Solution:
No Explaination.

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Q.2
A good current buffer has
A. low input impedance and low output impedance
B. low input impedance and high output impedance
C. high input impedance and low output impedance
D. high input impedance and high output impedance
Explaination / Solution:
No Explaination.

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Q.3
In the ac equivalent circuit shown in the figure, if iin is the input current and Rf is very larger, the type of feedback is A. voltage-voltage feedback
B. voltage-current feedback
C. current-voltage feedback
D. current-current feedback
Explaination / Solution:

From the circuit, we observe that output is Vout (Voltage). Feedback is current through resistance Rf , which is added to input current iin . Thus, the configuration is voltage-current feedback.

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Q.4
For the circuit shown below, taking the opamp as ideal, the output voltage Vout in terms of the input voltages V1 , V2 and V3 is A. 1.8V1 + 7.2V2 -V3
B. 2V1 + 8V2 - 9V3
C. 7.2V1 + 1.8V2 -V3
D. 8V1 + 2V2 - 9V3
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Q.5
In the circuit shown, the op-amp has finite input impedance, infinite voltage gain and zero input offset voltage. The output voltage Vout is A.

-I2 (R1 + R2)

B.

I2R2

C.

I1R2

D.

-I1 (R1 + R2)

Explaination / Solution:

Given that the op-amp has infinite voltage gain, i.e.

AOL

and zero input offset voltage

VIO = 0

So, we redraw the op-amp circuit as Hence, the current I1 is drawn through resistance R2. So, the output voltage is

Vout = I1R2

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Q.6
Group I gives two possible choices for the impedance Z in the diagram. The circuit elements in Z satisfy the conditions R2C2 > R1C1. The transfer functions V0/V1 represents a kind of controller. Match the impedances in Group I with the type of controllers in Group II
Group I                                                              Group II  A. Q - 1,R - 2
B. Q - 1,R - 3
C. Q - 2,R - 3
D. Q - 3,R - 2
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Q.7
The circuit shown is a A. B. C. D. Explaination / Solution: Workspace
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Q.8
The voltage gain Av of the circuit shown below is A. B. C. D. Explaination / Solution: Workspace
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Q.9
Consider the Schmidt trigger circuit shown below A triangular wave which goes from -12 to 12 V is applied to the inverting input of OPMAP. Assume that the output of the OPAMP swings from +15 V to -15 V. The voltage at the non-inverting input switches between A. -12V to +12 V
B. -7.5 V to 7.5 V
C. -5 V to +5 V
D. 0 V and 5 V
Explaination / Solution:

Let the voltage at non inverting terminal be V1, then after applying KCL at non inverting terminal side we have If V0 swings from -15 to +15 V then V1 swings between -5 V to +5 V.

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Q.10
The logic function implemented by the following circuit at the terminal OUT is A. P NOR Q
B. P NAND Q
C. P OR Q
D. P AND Q 