Of the four biasing circuits shown in Fig. For a BJT, indicate the one which can have maximum bias stability:

The transistor in the amplifier shown below has following parameters: $$${h_{fe}}\, = \,100,\,{h_{ie}}\, = \,2k\Omega ,\,{h_{re}}\, = \,0,$$$ $${h_{oe}}\, = \,0.05\,\,m\Omega .\,\,C$$ is very large.

The output impedance is

The amplifier circuit shown below uses a compostie transistor of a MOSFET and BIPOLAR in cascade. ALL capacitance are large. gm of the MOSFET = 2 mA/V , and h_fe of the BIPOLAR = 99. The overall Transconductance g_m of the composite transistor is

Each transistor in the Darlington pair (see Fig. below) has h_fe = 100. The overall h_fe of the composite transistor neglecting the leakage current is