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 _______.

In the circuit shown, I₁ = 80 mA and I₂ b= 4mA. Transistors T₁ and T₂ are identical. Assume that the thermal voltage V_T is 26 mV at 27^oC. At 50^oC, the value of the voltage V₁₂ = V₁ - V₂ (in mV) is _______.

For the common collector amplifier shown in the figure, the BJT has high $${V_{CE\left( {sat} \right)}},$$ and $${V_{BE}}$$ $$\, = \,\,0.7\,\,\,V$$. The maximum undistorted peak-to-peak output voltage $${V_o}$$ (in Volts) is _____.

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 ______.