1
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 _______.
2
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 _______.
3
GATE ECE 2014 Set 4
MCQ (Single Correct Answer)
+2
-0.6
Consider the common-collector amplifier in the figure (bias circuitry ensures that the transistor operates in forward active region, but has been omitted for simplicity). Let IC be the collector current, VBE be the base-emitter voltage and VT be the thermal voltage. Also, 𝑔m and 𝑟o are the small-signal transconductance and output resistance of the transistor, respectively. Which one of the following conditions ensures a nearly constant small signal voltage gain for a wide range of values of RE?
A
$${g_m}{R_E} < < \,1$$
B
$${I_C}{R_E} > > \,{V_T}$$
C
$${g_m}{R_o} > > \,1$$
D
$${V_{BE}}\, > > {V_T}$$
4
GATE ECE 2014 Set 4
Numerical
+2
-0
A BJT in common-base configuration is used to amplify a signal received by a $$50\,\Omega$$ antena. Assume kT/q = 25 mV. The value of the collector bias current ( in mA ) required to match the input impedance of the amplifier to the impedance of the antena is ______.