# Crystal Oscillators MCQ’s

This set of RF & Microwave Circuit Design Multiple Choice Questions & Answers (MCQs) focuses on “Crystal Oscillators”.

1. In an oscillator, the resonant feedback circuit must have must have a low Q in order to achieve stable oscillation.
a) true
b) false

2. Quartz crystals are more efficient as a feedback network because:
a) less circuit complexity
b) cost effective
c) crystals operate at high voltage levels
d) LC circuits have unloaded Q of a few hundreds

3. One condition to be satisfied in an oscillator circuit so that stable oscillations are produced is:
a) positive feedback is to be achieved
b) negative feedback is to be achieved
c) 1800 phase shift is required between the transistor input and output.
d) none of the mentioned

4. Quartz crystal and tourmaline used in oscillators work on the principle of:
a) photo electric effect
b) piezo electric effect
c) Raman effect

5. Quartz crystal is used in the _______region, where the operating point of the crystal is fixed.
a) resistive
b) inductive reactance
c) capacitive reactance
d) none of the mentioned

6. In the equivalent circuit of a quartz crystal, LCR arm has an inductance of 4 mH and capacitor has a value of 4nF, then the series resonant frequency of the oscillator is:
a) 0.25 MHz
b) 2.5 MHz
c) 25 MHz
d) 5 MHz

7. A quartz crystals equivalent circuit is a series LCR circuit and has a series resonant frequency.
a) true
b) false

8. In the plot of reactance v/s frequency of a crystal oscillator, the reactance between series resonant frequency and parallel resonant frequency is:
a) capacitive
b) inductive
c) both capacitive and inductive
d) none of the mentioned

9. Parallel resonant frequency of quartz crystal is given by:
a) 1/ √(LCₒC/(Cₒ+C))
b) 1/√LC
c) 1/√LCₒ
d) 1/ √(L(Cₒ+C) )

10. The equivalent circuit of a quartz crystal has LCR arm capacitance of 12nF and inductance of 3mH and parallel arm capacitance of 4nF. Parallel resonant frequency for the circuit is:
a) 3 MHz
b) 0.3 MHz
c) 6 MHz
d) 9 MHz