SRM University 2007 B.Tech Electronics and Communications Engineering EC202- ELECTRONIC CIRCUITS – II - Question Paper

22. A three part RC Phase shift oscillator has R=10KO and C=0.01µF.
(a) What is the frequency of oscillation?
(b) If the oscillator is to be made variable, using the identical values of R, what should be the
tuning range of the capacitor to find a frequency range of 1KHz to 100KHz.
23. Sketch a diode amplitude stabilization circuit for a Wein-Bridge oscillator and discuss its operation.
24. Calculate the operating frequency of a BJT Wein-Bridge oscillator for R=10KO and C=2400PF.
25. If the practical lower limit on C is 47PF in the Wein-Bridge oscillator,
(a) What should be the fixed value of R to produce an upper frequency limit of 200KHz?
(b) What should be the tuning range of C to give a lower frequency limit of 20 Hz?
26. What are the factors that affect the frequency stability of oscillators? discuss.
27. What is piezoelectric effect? Draw the crystal equivalent circuit?
28. Why Quartz crystal is preferred over other crystal in crystal oscillators?
29. Brief about occurrence of series and parallel resonant condition in crystal oscillators



Part – B

1. Sketch the block schematic of a general LC oscillator and find an expression for sustained oscillations using Barkhausen criteria for sine wave oscillation.

2. Sketch the circuit diagram for a Hartley oscillator using a single-stage BJT amplifier. discuss the circuit construction and operation. find expression for frequency of oscillation and condition for oscillation.

3. Sketch the circuit diagram for a Colpitts oscillator using a single-stage BJT amplifier. discuss the circuit construction and operation. find expression for frequency of oscillation and condition for oscillation.

4. Sketch the circuit diagram for a Clapp oscillator using a single-stage BJT amplifier. discuss the circuit construction and operation. find expression for frequency of oscillation and condition for oscillation.

5. Sketch the circuit diagram for a Tuned collector oscillator using a single-stage BJT amplifier. discuss the circuit construction and operation. Write expression for frequency of oscillation.

6. Sketch the circuit diagram for a Tuned Emitter oscillator using a single-stage BJT amplifier. discuss the circuit construction and operation. Write expression for frequency of oscillation.

7. Sketch the circuit diagram for a phase shift oscillator that uses a single stage BJT amplifier. discuss the circuit construction and operation. find an expression for frequency of oscillation.

Earning:   Approval pending.