QUESTION PAPER 6 DECEMBER 2015

Note: Attempt Any FIVE questions. All questions carry equal marks.
1. (a) What do you meant by transistor biasing? Explain with the help of DC load line concept.
In a certain transistor amplifier R1= 10KΩ, R2=5KΩ, Rc=1KΩ, RE = 2KΩ and RL= 1 KΩ and Vcc = 15V.
(i) Draw d.c load line, (ii) Determine the operating point. VBE = 0.7 (7 Marks)
(b) Explain the Base bias, emitter bias and voltage divider bias in detail. (7 Marks)
2. (a) Show the circuit of CE amplifier in detail and explain the function of each component. Develop D.C and A.C equivalent circuit and show both of them. (7 Marks)
(b) Certain CE amplifier has following data.R1=10KΩ, R2=5KΩ, Rc=3KΩ, RE=3KΩ, RL=6KΩ current gain β=50. Find the output voltage if input resistance Rin= 0.5KΩ
and input voltage Vin= 1mV. Also show the complete circuit diagram. (7 Marks)
3. (a) Explain frequency response curve of CE amplifier. Indicate Lower cutoff, higher cutoff and mid band frequencies. (7 Marks) (b) If R1= 16KΩ, R2= 22KΩ, RE = 900Ω and Vcc= 18V determine the values of VE and IE for emitter follower circuit. Also draw a D.C load line. (7 Marks)
4. (a) Explain in detail the positive and negative feed back circuits. (7 Marks)
(b) Define oscillator circuit. Explain the working of transistor Wein Bridge Oscillator. In A Wein bridge oscillator having R1=R2=220 KΩ and C1=C2= 250pF. Determine the frequency of oscillation. (7 Marks)
5.(a) Show the circuit of Hartley Oscillator and determine the operating frequency and feed back
fraction if L1= 1000μH, L2=100μH and C= 20PF. (7 Marks)
(b) Draw a circuit of RC phase shift oscillator and explain. A phase shift oscillator circuit uses 5pF capacitor. Find the value of R to produce frequency of 800KHz (7 Marks)
6.(a) Show the circuits of Operational amplifier as Inverting and non-inverting amplifier.
Derive the formula for voltage gain in both the cases. (7 Marks)
(b) Determine the output voltage for inverting and non-inverting amplifier circuit
having Rin= 2.4KΩ, Rf=240KΩ, and input voltage 120μV. Show the circuits as well.
(7 Marks)
7. Write short notes on any TWO. (2 x 7 Marks)
(a) Emitter follower circuit.
(b) Darlington Amplifier Circuit.
(c) Working of LC tank Circuit.
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