The 2 oscillator circuits below are suited to using crystal oscillators in sequence or parallel mode: Significant-repetition-price and significant-electricity picosecond regenerative amplifier according to one bulk Nd:GdVO4 crystal A timing reference incorporating only one-crystal-silicon micromechanical resonator with a high quality component of larger than a million in addition to a https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html