MES203TC
Electronic Circuits and Systems
2025-26 Semester 1- Assignment-002 CW
ASSIGNMENT-CW_002 (15 MARKS)
PLEASE ANSWER ALL THE FOLLOWING QUESTIONS (PAGE 2):
QUESTION 1:
(a) Suppose that the n-p-n transistor in Fig.1 is of Germanium with BVEBO = 10V and ICBO = 90uA. For VBB = 8V and RB = 9K, verify whether the transistor is in cutoff.
(b) What should be the maximum allowable value of RB to keep the transistor of part (a) in the cutoff region?
(c) Repeat the part (b) for a silicon transistor with BVEBO = 15V and ICBO = 50uA.
Fig.1: Reverse biasing of the emitter junction to maintain the transistor in cutoff in the presence of the reverse saturation current ICBO through RB.
(3 Marks)
QUESTION 2:
(a) Consider the transistor circuit of Fig. 2. For VCC = 10 V, VBB = 5 V, VBE = 0.7 V, Rb = 10 KΩ, Rc = 500 Ω, Re = 100 Ω and hFE = 100, calculate IB, IC, IE, VCB and VCE.
Fig.2
(b) If VBB is varied while maintaining other parameters unchanged in part (a), what is the minimum VBB required to drive the transistor into saturation? Assume that the collector-emitter voltage of the transistor at the saturation region is VCE (sat) = 0.3 V
(3 Marks)
QUESTION 3:
What is current mirror circuit? Explain with the help of figure and design equations. Design a Widlar current source for generating a constant current ICC = 10μA. Assume VCC = 10V, VBE= 0.7V, β = 125. Use Vт = 25mV.
(3 Marks)
QUESTION 4:
What is the importance of feedback-amplifier connections? Describe each feedback-amplifier connection with help of circuit diagram and detailed analysis.
(3 Marks)
QUESTION 5:
Find (a) the voltage gain with feedback AVsf , taking load and source resistances into account, (b) Rif, and (c) Rof for the feedback circuit of Fig.4a.
Fig. 4: (a) Emitter-follower amplifier circuit. (b) Approximate small-signal equivalent circuit
(3 Marks)