Small Signal Analysis

Question 1
The magnitude of the mid-band voltage gain of the circuit shown in figure is (assuming h_{fe} of the transistor to be 100)
A
1
B
10
C
20
D
100
GATE EE 2014-SET-1   Analog Electronics
Question 1 Explanation: 
AC model,



\; \; \; \; Z_{i}=10\, k\Omega
Mid band voltage gain \; \; \; \; A_{v}=\frac{A_{I}R_{L}}{Z_{i}}
\; \; \; \; A_{v}=\frac{-h_{fe}R_{L}}{Z_{i}} =\frac{-100\times 10\, k\Omega }{10\, k\Omega }=-100
\; \; \; \; \left | A_{v} \right |=100
Question 2
In the single-stage transistor amplifier circuit shown in figure, the capacitor C_{E} is removed. Then, the ac small-signal midband voltage gain of the amplifier
A
increases
B
decreases
C
is unaffected
D
drops to zero
GATE EE 2001   Analog Electronics
Question 2 Explanation: 
\frac{A_{V_1}}{A_{V_1}}=1+\left ( \frac{1+h_{fe}}{h_{ie}} \right )R_{e}
\frac{A_{V_{1}}}{A_{V_{2}}}> 1
\Rightarrow \; A_{V_{2}} \lt A_{V_{1}}
There are 2 questions to complete.
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