1
GATE ECE 2017 Set 1
Numerical
+2
-0
For the DC analysis of the Common-Emitter amplifier shown, neglect the base current and assume that the emitter and collector current are equal. Given that VT = 25mV, VBE = 0.7V, and the BJT output r0 is practically infinite. Under these conditions the midband voltage gain magnitude, av = $$\left| {{v_0}/{v_i}} \right|\,\,\,V/V,$$ is _____
2
GATE ECE 2017 Set 1
Numerical
+2
-0
In the figure shown, the npn transistor acts as a switch.

For the input vin(t)as shown in the figure, the transistor switches between the cut-off and saturation regions of operation, when T is large. Assume collector-to-emitter voltage saturation VCE(sat) = 0.2V and base-to-emitter voltage VBE = 0.7V. The minimum value of the common-base current gain$$\left( \alpha \right)$$ of the transistor for the switching should be _________.

3
GATE ECE 2015 Set 2
Numerical
+2
-0
In the ac equivalent circuit shown, the two BJTs are biased in active region and have identical parameters with β >> 1. The open circuit small signal voltage gain is approximately _______.
4
GATE ECE 2015 Set 1
Numerical
+2
-0
In the circuit shown, I1 = 80 mA and I2 b= 4mA. Transistors T1 and T2 are identical. Assume that the thermal voltage VT is 26 mV at 27oC. At 50oC, the value of the voltage V12 = V1 - V2 (in mV) is _______.