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Electronics and Communication Engineering - Analog Electronics

Exercise : Analog Electronics - Section 3
26.
Which of the following?
Voltage series feedback and decrease I/P impedance.
Voltage shunt feedback and decrease I/P impedance.
Voltage series feedback and increase I/P impedance.
Voltage shunt feedback and increase I/P impedance.
Answer: Option
Explanation:

Because sample signal is voltage and feedback signal is also voltage. The drop in RE change the input voltage at Base Emitter Junction.

27.
In a transistor E mode the collector current with the transistor in cut off region is
zero
high
equal to saturated value
none of the above
Answer: Option
Explanation:

When transistor is cut off, IC is zero.

28.
Two CE stages, 1 and 2 are coupled through a capacitor. VCC is the same for both. Base resistances RB1 and RB2 are such that RB1 > RB2. Then
base currents for both stages are equal
base current of stage 1 is more than that of stage 2
base current of stage 2 is more than that of stage 1
either (b) or (c)
Answer: Option
Explanation:

Since RB2 < RB1, IB2 > IB1.

29.
In a two stage CE amplifier circuit, the ac collector resistance of the first stage depends on
load resistance
input impedance of first stage
input impedance of second stage
all of the above
Answer: Option
Explanation:

Since the first amplifier is feeding the second stage, the input impedance of second stage is the ac collector resistance of first stage.

30.
In a CE amplifier the ac cut off voltage is 9 V and slope of ac load line is - 0.5 mA/V. The ac saturation current is
9 mA
4.5 mA
3 mA
18 mA
Answer: Option
Explanation:

AC saturation current is cutoff voltage x slope of ac load line.

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