Analog electronics circuits miscellaneous Easy Questions and Answers | Page - 63

Analog electronics circuits miscellaneous

Assume that the op-amp shown below is ideal. The current I through the 1 kΩ resistor is:

1. – 4 mA
1. – 2 mA
1. 2 mA
1. 4 mA

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Due to virtual ground voltage at terminal A is 0 V. KCL at node A
2 = V_A – V_B
2

2 = 0 – V_B
2

or V_B = – 4 V
Again KCL at B
I = V_B – V_A + V_B – 0
2 2

or I = (–4 – 0) + –4
2 2

or I = – 2 – 2 I = – 4 mA
Hence alternative (A) is the correct choice.

Correct Option: A

Due to virtual ground voltage at terminal A is 0 V. KCL at node A
2 = V_A – V_B
2

2 = 0 – V_B
2

or V_B = – 4 V
Again KCL at B
I = V_B – V_A + V_B – 0
2 2

or I = (–4 – 0) + –4
2 2

or I = – 2 – 2 I = – 4 mA
Hence alternative (A) is the correct choice.

In the op-amp circuit V₀ is given by:

1. 2 V_s
1. – 2 V_s
1. 3 V_s
1. – 3 V_s

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Due to virtual ground voltage at terminal A is V_s KCL at node A.
V_s + V_s – V_o = 0
R 2R

V_s + V_s = V_o
R 2R 2R

V_s 3R = V_o
2R² 2R

or V₀ = 3 V_s
Alternative method
V₀ = V_s 1 + 2R = 3 V_s
R

Correct Option: C

Due to virtual ground voltage at terminal A is V_s KCL at node A.
V_s + V_s – V_o = 0
R 2R

V_s + V_s = V_o
R 2R 2R

V_s 3R = V_o
2R² 2R

or V₀ = 3 V_s
Alternative method
V₀ = V_s 1 + 2R = 3 V_s
R

The circuit shown below is:

1. an adder
1. substractor
1. differentiator
1. integrator

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NA

Correct Option: D

NA

For the 2N 338 transistor the manufacturer specifies P_max = 100 mW at 25ºC free-air temperature and maximum junction temperature, T_jmax = 125ºC. Its thermal resistance is:

1. 10º C/W
1. 100º C/W
1. 1000º C/W
1. 10000º C/W

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Given T_{j man} = 125ºC
T_A = 25ºC
P_max = 100 mW
Q_jc = thermal resistance =?
from the relation
Q_jc = T_{j (max)} – T_ambient
P_max

= 125 – 25
100 mw

= 100 = 1000° C/W
100 × 10^–3

Correct Option: C

Given T_{j man} = 125ºC
T_A = 25ºC
P_max = 100 mW
Q_jc = thermal resistance =?
from the relation
Q_jc = T_{j (max)} – T_ambient
P_max

= 125 – 25
100 mw

= 100 = 1000° C/W
100 × 10^–3

In order to reduce the harmonic distortion in an amplifier the dynamic range has to be:

1. controlled
1. expanded
1. compressed
1. modified

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In order to reduce the harmonic distortion in an amplifier say class-B push pull amplifier, where all the even harmonics gets cancelled or we can say that the dynamic range of the amplifier becomes compressed.
Hence alternative (C) is the correct choice.

Correct Option: C

In order to reduce the harmonic distortion in an amplifier say class-B push pull amplifier, where all the even harmonics gets cancelled or we can say that the dynamic range of the amplifier becomes compressed.
Hence alternative (C) is the correct choice.