Requests for information


Joined Oct 2, 2009
Off the top of my head, one simple explanation is - crystals are tuned circuits. Loading capacitors help to lock in to the resonant frequency.

Another reason is - crystals have different modes of oscillations, most commonly, fundamental and third harmonic.
Capacitors help the crystal to oscillate at one preferred frequency.

You can read this:


Joined Jun 22, 2012
The capacitors are there to resonate with the crystal inductance and cause the crystal to oscillate on its fundamental parallel-resonant mode. ... The difference between a crystal with two capacitors compared to a ceramic resonator is that the capacitors happen to be integrated into the ceramic resonator.