The two oscillator circuits under are suitable for employing crystal oscillators in series or parallel method: Higher-repetition-amount and high-electricity picosecond regenerative amplifier dependant on just one bulk Nd:GdVO4 crystal A timing reference incorporating an individual-crystal-silicon micromechanical resonator with an excellent factor of greater than a million in addition ... https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html