Crystal oscillators are loosely divided because of the frequency they function at and whether or not they are essential oscillators—work in the frequency marked within the can or at even multiples of that (overtone oscillators). Substantial-repetition-charge and higher-power picosecond regenerative amplifier dependant on one bulk Nd:GdVO4 crystal A timing reference https://iowa-bookmarks.com/story14613707/bulk-crystal-oscillator-an-overview