Crystal oscillators are loosely divided from the frequency they operate at and whether they are elementary oscillators—function within the frequency marked within the can or at even multiples of that (overtone oscillators). As you can see from your graph underneath, crystals have two resonant points. A reduced impedance collection resonance https://bookmarkssocial.com/story18893069/the-smart-trick-of-bulk-crystal-oscillator-that-no-one-is-discussing