Elec Circuits & Comm. Fundamentals - May 2012

Computer Engineering (Semester 3)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1(a) Draw re model and h model of CE amplifier configuration(4 marks) 1(b) Investigate the effect of I_b on the performance of inverting amplifier, if I_b=10nA and all resistances are 100K ohm. What dummy resistance R_p must be installed in series with the non-inverting input to minimize E₀?(4 marks) 1(c) List features of IC 723 regulator(4 marks) 1(d) Explain two static and dynamic parameters of op-amp(4 marks) 1(e) Why voltage divider biasing is widely used?(4 marks) 2(a) Draw the circuit diagram of 3 op-amp instrumentation amplifier using IC741. Explain its requirements, applications and its disadvantages over difference amplifier.(12 marks) 2(b) Derive equations for Z_i, Z₀ and A_v for CE amplifier using voltage divider network (with un-bypassed R_e)(8 marks) 3(a) Why is an emitter coupled differential amplifier RE resistor is replaced by constant current source. Draw such circuit. Explain how this network acts as a constant current source (I₀)(10 marks) 3(b) For n-channel FET (un-bypassed Rs) with R1=910k ohm, R2=110k ohm , RD=2.2k ohm , RS= 510 ohm, IDSS=5.8mA , Vp=-3V and VGSS=-2V. Find ID, VGS, VG, VD, VS, and VDS (common source circuit)(10 marks) 4(a) Design a mono-stable multi-vibrator to generate a pulse of 1.1ms. Draw circuit diagram with trigger circuits waveforms obtained at pin 3 across capacitor.(10 marks) 4(b) Draw and explain working of R-2R ladder network and the following terms:
i. Resolution
ii. Offset voltage
iii. Full scale voltage(10 marks) 5(a) Draw and explain block diagram of IC 723 regulator and also explain need of short circuit protection circuitory(10 marks) 5(b) Draw neat functional diagram of PLL IC 555 and explain the following terms along with working of PLL:
i. Free running frequency
ii. Capture range
iii. Lock range(10 marks) 6(a) Explain Op-amp as summer and comparator(10 marks) 6(b) Compare ideal and practical integrator circuit(10 marks) 7(a) Schmitt trigger circuit(5 marks) 7(b) Successive approximation resistor analogue to digital convertor(5 marks) 7(c) FET characteristics(5 marks) 7(d) Wein bridge Oscillator(5 marks) 7(e) Stability factor of biasing circuit.(5 marks)