text: Frequency stability Temperature changes, aging, and manufacturing tolerances will cause component values to "drift" away from their designed values. Changes in frequency determining components such as the tank circuit in LC oscillators will cause the oscillation frequency to change, so for a constant frequency these components must have stable values. How stable the oscillator's frequency is to other changes in the circuit, such as changes in values of other components, gain of the amplifier, the load impedance, or the supply voltage, is mainly dependent on the Q factor ("quality factor") of the feedback filter. Since the amplitude of the output is constant due to the nonlinearity of the amplifier (see Startup section below), changes in component values cause changes in the phase shift  of the feedback loop. Since oscillation can only occur at frequencies where the phase shift is a multiple of 360°, , shifts in component values cause the oscillation frequency  to change to bring the loop phase back to 360n°. The amount of frequency change  caused by a given phase change  depends on the slope of the loop phase curve at , which is determined by the
  so
  RC oscillators have the equivalent of a very low , so the phase changes very slowly with frequency, therefore a given phase change will cause a large change in the frequency. In contrast, LC oscillators have tank circuits with high  (~102).  This means the phase shift of the feedback network increases rapidly with frequency near the resonant frequency of the tank circuit. So a large change in phase causes only a small change in frequency.  Therefore the circuit's oscillation frequency is very close to the natural resonant frequency of the tuned circuit, and doesn't depend much on other components in the circuit.  The quartz crystal resonators used in crystal oscillators have even higher  (104 to 106) and their frequency is very stable and independent of other circuit components.