The two oscillator circuits down below are appropriate for using crystal oscillators in sequence or parallel manner: Higher-repetition-fee and high-electricity picosecond regenerative amplifier dependant on an individual bulk Nd:GdVO4 crystal A timing reference incorporating an individual-crystal-silicon micromechanical resonator with an excellent aspect of greater than a million in a... https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html