7.a) With neat sketches and necessary waveforms, explain the input and output characteristics of a BJT in CE configuration. Also derive expression for output current. b) Calculate the collector current and emitter current for a transistor with a 0.99 and ICBO= 50A when the base current is 20A. 8.a) Explain the basic requirements of transistor biasing. Verify these requirements in collector to base bias circuit. b) Design a fixed bias circuit using silicon transistor, with the following specifications: VCC = 16V, VBE 0.7V, VCEQ= 8V, ICQ = 4 mA & = 50. OR 9.a) What is thermal runaway in transistors? Obtain the condition for thermal stability in transistors. b) Draw the circuit diagram, AC equivalent & small signal equivalent of Emitter Follower amplifier using accurate h-parameter model. Derive expressions for AVS, AIS, RI & RO. 10.a) Explain the construction & operation of an N-channel enhancement and depletion MOSFET with the help of static drain characteristics and transfer characteristics. b) Define pinch-off voltage and transconductance in field effect transistors. OR 11(a) Write short notes on applications of FET as a voltage variable resistor. b) Explain the principle of CS amplifier with the help of circuit diagram. Derive the expressions for A input impedance and output impedance.