EX-305 Analog Electronics - Jun 2023 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 8 Marks
   aExplain the Tunnel diode operation and V-I characteristics with the help of necessary diagrams.
   How to answer

   • Define tunnel diode heavy doping and tunneling mechanism
   • Explain forward V-I regions including negative resistance with energy band view
   • Draw V-I characteristics marking peak, valley, forward voltages
   • Mention applications
2. 6 Marks
   bA LC filter is used to provide a DC output with 1% ripple from a FWR operating at 50 Hz. Assuming L/C=0.01 determine L and C values.
   How to answer

   • Ripple factor formula for LC / L-section filter with FWR
   • Use given L/C ratio and 1% ripple condition
   • Solve for L and C at 50 Hz supply (100 Hz ripple frequency)
   • State final L in H and C in F with units
3. 6 Marks
   aExplain voltage multiplier circuits and mention its applications.
   How to answer

   • Define voltage multiplier principle using clamp and rectifier stages
   • Explain doubler, tripler, quadrupler operation with waveforms
   • Draw circuit diagrams
   • List applications like CRT, HV supplies
4. 8 Marks
   bDetermine the value of $I_c$ and $V_{ce}$ for the Fixed bias circuits with components $R_B=300K$, $R_C=2K$, $\beta=50$ and $V_{CC}=9V$ as shown below.

   

   How to answer

   • Write base current expression Ib = (Vcc-Vbe)/Rb
   • Calculate Ic = beta*Ib
   • Apply KVL at collector to get Vce = Vcc - Ic*Rc
   • State numerical values with units
5. 7 Marks
   aDiscuss load line analysis.
   How to answer

   • Define DC load line from KVL and Q-point
   • Explain cutoff, saturation and active region intercepts
   • Discuss selection of Q-point and AC load line
   • Draw load line on output characteristics
6. 7 Marks
   bA self biased p-channel JFET has pinch-off voltage of $V_P=5V$ and $I_{DSS}=12mA$. The supply voltage is 12V. Determine the values of $R_D$ and $R_S$ so that $I_D=5$ mA and $V_{DS}=6V$.
   How to answer

   • Use JFET drain current equation Id = IDSS*(1-Vgs/Vp)^2 with polarities for p-channel
   • Apply KVL: Vgs = Id*Rs and Vds relations
   • Solve for Rs and Rd to get Id=5 mA, Vds=6V with 12V supply
   • Verify values
7. 7 Marks
   aDerive the expression for frequency of oscillations in RC Phase shift oscillator.
   How to answer

   • Draw RC phase shift oscillator with three RC sections and transistor/op-amp
   • Apply Barkhausen criterion and nodal analysis
   • Derive oscillation condition and gain requirement
   • Obtain frequency expression f = 1/(2*pi*RC*sqrt(6))
8. 7 Marks
   bThe RC network of Wein bridge oscillator consists of registers and capacitors of values $R_1=R_2=220\text{ k}\Omega$ and $C_1=C_2=250\text{ PF}$. Determine frequency of oscillation.
   How to answer

   • Write Wien bridge frequency formula f = 1/(2*pi*R*C)
   • Substitute R1=R2=220 kΩ and C1=C2=250 pF
   • Calculate numerical frequency
   • State result in Hz/kHz
9. 7 Marks
   aExplain different types power amplifiers based on selection of an operating point along with diagrams.
   How to answer

   • Define classes A, B, AB, C by Q-point position and conduction angle
   • Draw operating point on load line and output waveforms for each
   • Compare efficiency and distortion
   • Mention applications
10. 7 Marks
    bFor a class B power amplifier using a supply voltage of Vcc = 24V, and driving a load of $8\Omega$. Determine the maximum load power, DC input power and collector efficiency if the peak to peak output voltage across the load resistance is 22V.
    How to answer

    • Compute peak voltage from 22V peak-to-peak
    • Calculate maximum load power Po = Vm^2/(2*RL)
    • Calculate DC input power Pdc = 2*Vcc*Im/pi
    • Compute efficiency eta = Po/Pdc
11. 7 Marks
    aDiscuss clipper and how a double ended clipper with equal and unequal amplitude can be implemented explain with suitable example and diagram.
    How to answer

    • Define clipper and its purpose
    • Explain single and double-ended clipping with diode circuits
    • Show equal and unequal amplitude clipping with examples and waveforms
    • Draw transfer characteristics
12. 7 Marks
    bExplain Darlington pair transistor circuit.
    How to answer

    • Draw Darlington pair connection of two transistors
    • Explain current gain multiplication
    • Derive overall beta and input impedance
    • Mention advantages and applications
13. 7 Marks
    aHow an integrator can be implemented using Op-Amp and show the output waveform when integrator circuit is applied with sinusoidal and square wave as an input.
    How to answer

    • Draw op-amp integrator with R input and C feedback
    • Derive output Vo = -1/RC integral Vi dt
    • Show sine input gives cosine output and square gives triangular output
    • Draw input-output waveforms
14. 7 Marks
    bCalculate cutoff frequency and pass band gain for second order low pass filter if $R=27K\Omega$, $R_F=7K\Omega$, $R_1=R_2=33K\Omega$, $C_1=C_2=0.0047\mu F$.
    How to answer

    • Write cutoff frequency formula for second order low pass filter
    • Substitute R1=R2 and C1=C2 values
    • Calculate pass band gain from RF and R
    • State fc and gain values
15. 14 Marks
    Write a short note on any four of the following:

    1. a)Varactor diode
    2. b)Enhancement mode MOSFET
    3. c)Crystal oscillator
    4. d)Bistable multivibrator
    5. e)Op-Amp as summer
    How to answer

    • Define each device/circuit briefly
    • Draw relevant characteristics or circuit diagram
    • Explain working principle
    • Mention key applications