1
GATE ECE 2001
MCQ (Single Correct Answer)
+2
-0.6
An npn BJT has gm = 38 mA/V, $${C_\mu }\, = {10^{ - 14}}$$ F, $${C_\pi }\, = 4\, \times {10^{ - 13}}\,F$$ and DC current gain $$\beta \, = \,90$$. For this transistor fT and $${f_\beta }$$ are
A
\eqalign{ & {f_T} = 1.64 \times {10^8}\,\,Hz\,and \cr & {f_\beta } = 1.47 \times {10^{10}}\,\,Hz \cr}
B
\eqalign{ & {f_T} = 1.47 \times {10^{10}}\,\,Hz\,and \cr & {f_\beta } = 1.64 \times {10^8}\,\,Hz \cr}
C
\eqalign{ & {f_T} = 1.33 \times {10^{12}}\,\,Hz\,and \cr & {f_\beta } = 1.47 \times {10^{10}}\,\,Hz \cr}
D
\eqalign{ & {f_T} = 1.47 \times {10^{10}}\,\,Hz\,and \cr & {f_\beta } = 1.33 \times {10^{12}}\,\,Hz \cr}
2
GATE ECE 1999
MCQ (Single Correct Answer)
+2
-0.6
An NPN transistor (with $${C_\pi }\,\, = \,\,0.3\,\,$$ pf) has a unity gain cutoff frequency $${f_T}$$ of 400 MHz at a DC-bias current Ic = 1mA. The value of its $${C_\mu }$$ (in pf) is approximately $$\left( {{V_T}\, = \,26\,mV} \right)$$.
A
15
B
30
C
50
D
96
3
GATE ECE 1999
MCQ (Single Correct Answer)
+2
-0.6
An amplifier is assumed to have a single pole high frequency transfer function. The rise time of its output response to a step function input is 35 nsec. The upper 3 dB frequency (in MHz) for the amplifier to a sinusoidal input is approximately at
A
4.55
B
10
C
20
D
28.6
4
GATE ECE 1996
MCQ (Single Correct Answer)
+2
-0.6
In the circuit shown in Fig. is a finite gain amplifier with a gain of K, a very large input impedance, and a very low output impedance. The input impedance of the feedback amplifier with the feedback impedance Z conducted as shown will be
A
$$Z\left[ {1 - {1 \over K}} \right]$$
B
$$Z\left( {1 - K} \right)$$
C
$$\left[ {{Z \over {K - 1}}} \right]$$
D
$$\left[ {{Z \over {1 - K}}} \right]$$
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