The two oscillator circuits under are well suited for utilizing crystal oscillators in sequence or parallel mode: Large-repetition-level and higher-electricity picosecond regenerative amplifier based on an individual bulk Nd:GdVO4 crystal A timing reference incorporating one-crystal-silicon micromechanical resonator with a quality element of much larger than a million along with a https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html