Clean Output Crystal Oscillator

An oscillator circuit which exhibits extremely low power dissipation in the crystal, giving good frequency stability. 

Capacitors C1 and C2 must be selected according to the frequency range as shown.

While most designers use almost the same value capacitor at both C1 and C2, the capacitance of C1 should be substantially higher than C2. This reduces the influence of the transistor on the stability of the circuit by more than five times. 

In the circuit the output voltage is taken across the parallel RC circuit made up by capacitor C3 and resistor R1, a 22-ohm resistor. Together with the crystal,  R1 and C3 form a low-pass filter which suppresses the second harmonic by 60 dB.