The two oscillator circuits under are suitable for employing crystal oscillators in series or parallel method: High-repetition-fee and superior-electrical power picosecond regenerative amplifier based upon a single bulk Nd:GdVO4 crystal 中原子或分子的排列具有三维空间的周期性，隔一定的距离重复出现，这种周期性规律是 The kind of amplifier you'll need will depend upon the frequency. Op-am... https://www.hxcrystals.com/seokeywords/bulk-crystal-oscillator.html