The 2 oscillator circuits beneath are well suited for employing crystal oscillators in series or parallel manner: Substantial-repetition-price and higher-ability picosecond regenerative amplifier based upon an individual bulk Nd:GdVO4 crystal A timing reference incorporating a single-crystal-silicon micromechanical resonator with an outstanding element of bigger than a million plus a ... https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html