# Analog Circuits Questions and Answers – Crystal Oscillator-1

This set of Analog Circuits Interview Questions and Answers for Experienced people focuses on “Crystal Oscillator-1”.

1. Which of the following are not the characteristics of a crystal oscillator?
a) Highly stable with time
b) Highly stable with temperature
c) Highly selective
d) Frequency depends external resistors and capacitors

Explanation: The crystal oscillator is highly stable with time, highly stable with temperature, highly selective. The frequency of crystal is a constant regardless of output circuits. The frequency is dependent on the crystal shape which does not differ much at all.

2. Equivalent circuit of crystal oscillator contains ______________
a) Two inductors and two capacitors
b) One inductors and two capacitors
c) Two inductors and one capacitors
d) One inductors and one capacitors

Explanation: There is one inductor in series with a resistor and a capacitor, which are all in parallel to a second capacitor. The whole setup acts like a crystal oscillator and the values of these components determine the resonant frequency.

3. The parallel capacitance in the equivalent circuit of crystal oscillator represents __________
a) Inter electrode capacitance
b) Compliance
c) Viscous factor
d) Mass

Explanation: The parallel capacitor of the equivalent circuit of crystal oscillator constitute for electrostatic capacitance between two parallel plates of crystal. That is, it is inter electrode capacitance. It represents the capacitance formed due to mechanical moulding of the crystal.

4. The inductance in the equivalent circuit of crystal oscillator represents __________
a) Inter electrode capacitance
b) Compliance
c) Viscous factor
d) Mass

Explanation: Inductance of the crystal oscillator physically refer to mass of the oscillator.

5. The series capacitance in the equivalent circuit of crystal oscillator represents __________
a) Inter electrode capacitance
b) Compliance
c) Viscous factor
d) Mass

Explanation: The series capacitance of the oscillator physically represents the compliance of the oscillator.
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6. The resistance in the equivalent circuit of crystal oscillator represents __________
a) Inter electrode capacitance
b) Compliance
c) Viscous factor
d) Mass

Explanation: The resistance in the equivalent circuit represents the friction of the crystal’s internal structure, or we can say the viscous factor of the crystal.

7. When frequency of oscillation of a crystal oscillator becomes parallel resonance frequency reactance of crystal oscillator becomes __________
a) Zero
b) Infinity
c) Unpredictable
d) Unity

Explanation: The oscillator has two resonant frequencies, parallel and series. Parallel resonance occurs when the reactance of series leg becomes equal to that of the parallel capacitor, and during this time, impedance offered is very high, almost infinite.

8. When frequency of oscillation of circuit is less than series resonance frequency wS crystal oscillator act as __________
a) Inductor
b) Capacitor
c) Resistor
d) Transistor

Explanation: When the frequency of oscillation of crystal becomes less than that of wS the oscillator becomes capacitive and in between wS and wP it becomes inductive.

9. The reactance of crystal oscillator will be inductive if oscillator operating frequency is __________
a) Greater than parallel resonance frequency
b) Less than series resonance frequency
c) In between parallel resonance frequency and series resonance frequency
d) Greater than series resonance frequency

Explanation: When the frequency of oscillation of crystal becomes less than that of wS the oscillator becomes capacitive and in between wS and wP it becomes inductive.

10. The crystal can be used to replace inductor in __________
a) RC phaseshift oscillator oscillator
b) Colpitts oscillator
c) Clapp oscillator
d) Weinbridge oscillator

Explanation: Crystal oscillator operating between wS and wP is inductive and hence we can replace it with inductor in colpitts oscillator.

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