1
GATE ECE 2011
+2
-0.6
For the BJT Q1 in the circuit shown below, $$\beta = \infty ,\,\,\,\,{V_{BEon\,}}\, = \,0.7V,\,\,\,{V_{CEsat}}\, = \,0.7V.$$. The switch is initially closed. at time t = 0, the switch is opened. The time t at which q1 leaves the active region is
A
10 ms
B
25 ms
C
50 ms
D
100 ms
2
GATE ECE 2009
+2
-0.6
A small signal source Vi(t) = A cos 20t + B sin 106 t, is applied to a transistor Amplifier as shown in fig. The transistor has $$\beta$$ = 150 and hie = 3k$$\Omega$$ , which expression best approximates $${V_0}\left( t \right)$$ ?
A
$$V_o\left( t \right)\,\, = \, - 1500\,\left( {{\rm A}\,\cos 20t\, + b\sin \,{{10}^6}t} \right)$$
B
$${V_o}\,\left( t \right)\,\, = \, - 1500\,\left( {{\rm A}\,\cos 20t\, + b\sin \,{{10}^6}t} \right)$$
C
$${V_o}\left( t \right)\,\, = \, - 1500\,B\sin \,{10^6}t$$
D
$${V_o}\left( t \right)\,\, = \, - 150\,B\sin \,{10^6}t$$
3
GATE ECE 2008
+2
-0.6
In the following transistor circuit, VBE = 0.7V, re = 25m/IE, $$\beta$$ and all the capacitances are very large.

The Value of DC current IE is

A
1 mA
B
2 mA
C
5 mA
D
10 mA
4
GATE ECE 2008
+2
-0.6
In the following transistor circuit, VBE = 0.7V, re = 25m/IE, $$\beta$$ and all the capacitances are very large.

The mid-band voltage gain of the amplifier is approximately

A
-180
B
-120
C
-90
D
-60
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