In colpitts oscillator ,showed as figure, There is as DC bias voltage between crystal.
In my circuit, it will be 600mV.
1. Doese this bias voltage create damage to cyrstal ?
2. Does it make freqency of ocsillator inaccuracy?
Look at the equivalent circuit of a crystal and you will see that a DC voltage of 600mV won't affect the crystal. What is more important is to keep the AC current flowing through the crystal low as to limit power dissipation in the crystal's internal series resistance. Too high dissipation can accelerate aging (cause frequency drift) and even damage the crystal.