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Electronics and Communication Engineering - Analog Electronics

Exercise : Analog Electronics - Section 6
6.
In a negative feedback amplifier A = 100, β = 0.04 and Vs = 50 mV, then feedback will be
4
8
10
2
Answer: Option
Explanation:

Feed back factor (βA) = 4.

7.
For an npn transistor connected as shown in the figure VBE = 0.7 volts. Given that reverse saturation current of the junction at room temperature 300K is 10-13A, the emitter current.
30 mA
39 mA
49 mA
20 mA
Answer: Option
Explanation:

IE = aIE + ICBO and approximated.

But a is not given in the question. It is not possible to find.

8.
The dc output voltage of the circuit is
4.3 V
1.369 V
3.87 V
1.94 V
Answer: Option
Explanation:

This is half wave Rectifier, because in +ve cycle both the diode will be in forward biased.

For +ve cycle,

Vo max = Imax. Req

2.59 x 10-3 x 1.66 x 103

4.299 volt.

9.
A voltage doubler circuit is fed by a voltage Vm sin ωt. The output voltage will be nearly 2 Vm only if
load resistance is small
load resistance is large
load resistance is neither small nor large
either (a) or (c)
Answer: Option
Explanation:

If load resistance is large, current would be low and voltage drop would be low.

10.
The purpose of connecting a coupling capacitor in the output circuit of an amplifier is
to increase voltage gain
to increase collector current
to block dc collector voltage
all of the above
Answer: Option
Explanation:

Capacitor acts for ac or dc.

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