1
GATE ECE 2014 Set 3
Numerical
+1
-0
In the circuit shown, the PNP transistor has $$\left|{\mathrm V}_\mathrm{BE}\right|=0.7\;\mathrm V$$ and β = 50. Assume that RB = 100 kΩ. For V0 to be 5 V, the value of RC ( in kΩ) is _____________.
2
GATE ECE 2014 Set 2
Numerical
+1
-0
A cascade connection of two voltage amplifiers A1 and A2 is shown in the figure. The open-loop gain Av0, input resistance Rin, and output resistance R0 for A1 and A2 are as follows:
A1: Av0 = 10,Rin = 10 kΩ ,R0 =1 kΩ
A2 : Av0 = 5,Rin = 5 kΩ , R0 = 200 Ω
The approximate overall voltage gain $$\frac{{\mathrm V}_\mathrm{out}}{{\mathrm V}_\mathrm{in}}$$ is ______.
3
GATE ECE 2012
+1
-0.3
The current ib through the base of a silicon npn transistor is $$1\;+\;0.1\;\cos\left(10000\;\mathrm\pi\;\mathrm t\right)$$ mA . At 300 K, the $$r_\mathrm\pi$$ in the small signal model of the transistor is
A
$$250\;\Omega$$
B
$$27.5\;\Omega$$
C
$$25\;\Omega$$
D
$$22.5\;\Omega$$
4
GATE ECE 2011
+1
-0.3
In the circuit shown below, capacitors C1 and C2 are very large and are shorts at the input frequency. Vi is a small signal input. The gain magnitude $$\left|\frac{{\mathrm V}_0}{{\mathrm V}_\mathrm i}\right|$$ at 10 Mrad/s is
A
maximum
B
minimum
C
unity
D
zero
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