Test: Crystal Oscillator - Electronics and Communication Engineering (ECE) MCQ

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.

 There is One inductor two capacitor and one resistor in equivalent circuit of crystal oscillator. Values of these components determines the resonance frequency of oscillation.

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.

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

Series capacitance of oscillator is physically representing the complaints of oscillator.

Resistance in the equivalence circuit of the crystal oscillator physically refers to viscous factor of the crystal.

When resonance frequency of oscillator becomes parallel resonance frequency the impedance of the oscillator becomes infinity.

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.

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.

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

When a voltage source is applied to a quartz crystal, it begins to produce a characteristic known as the Piezo electric effect. It is a property of a crystal by which an electrical charge produces a mechanical force by changing the shape of the crystal and vice versa, a mechanical force applied to the crystal produces an electrical charge.

For critical applications the quartz oscillator is mounted in a temperature-controlled container. It is called a crystal oven, and can also be mounted on shock absorbers to prevent perturbation.

The crystal frequency will only depend on internal characteristics of the crystal and hence it depends on shape or ’cut’ of the crystal.

The crystal resonator frequency will change according to operating time, this phenomenon is termed as aging.

 When power is removed from an oscillator for several hours, then re-applied on it again, the frequency of this oscillator will stabilize at a slightly different value. This frequency variation error is called retrace error.

Measure of sensitivity of crystal oscillator output frequency to supply voltage is called
Frequency pulling. It is represented in MHz/V.

The measure of frequency change due to non- ideal load is called frequency pulling.

maximum available tuning voltage to the required tuning-frequency range
Is indicated by Oscillator turning port noise.

Vibration induced noise caused due to sensitivity to acceleration of crystal.