Answer:CRYSTAL OSCILLATOR

CRYSTAL OSCILLATOR CIRCUIT DIAGRAM

1. Above shown is a crystal oscillator,in which the inductor is replaced by a crystal;usually quartz.It is used in place of the LC circuit as a resonating circuit.
2. When the voltage feedback increases,the crystal impedance also decreases.
3. The resonant frequency is inversely proportional to the thickness of the crystal i.e., f = k/t.
4. Here, the series resonant frequencyfs = $1 \over 2\pi \sqrt(LC_s)$ and the parallel resonant frequencyfp = $1\over2 \pi\sqrt(LC_ (eq) )$ ,where Ceq =$C_1C_m \over(C_1+C_m)$
5. Crystal Oscillators have high order of frequency stability.
6. Crystal Oscillators have high frequency of oscillation but it cannot be changed appreciably