Quality Factor

The quality factor defines the sharpness of resonance.

It is defined as:

where

Q = quality factor

ω₀ = resonance frequency [rads^-1]

ω₁ = is the frequency below resonance for which the average power has dropped to half that at resonance [rads^-1]

ω₂ = is the frequency above resonance for which the average power has dropped to half that at resonance [rads^-1]

It is an inherent characteristic of an oscillator that influences its stability. Generally speaking, the higher the Q, the more stable the oscillator, since a high Q means that an oscillator will stay close to its natural resonance frequency.

Examples

Oscillator Type	Quality Factor, Q
Tuning Fork	103
Quartz Wristwatch	104
Oven Controlled Crystal Oscillator	106
Rubidium	107
Caesium Beam	108
Hydrogen Maser	109
Caesium Fountain	1010
Mercury Ion Optical Standard	1014

See also: Resonance.