A suspended crystal: reading a quartz resonator package
A cutaway metal cover reveals the crystal and its supports. The open assembly shows how a delicate resonating element can be held inside a protective package.
Inside the assembly
A pale circular quartz plate carries electrodes on opposite faces. Two leads support and connect the plate above a ceramic base. Feedthroughs and external pads complete the electrical path while the rear half of the metal cover remains visible. The shape and dimensions are illustrative, with no assigned frequency.
Scientific explanation
Piezoelectric coupling links electrical excitation to mechanical vibration. Near one resonance, a motional inductance and capacitance provide an equivalent electrical description. Their series resonance is set by the expression below; package capacitance and the external circuit affect operating frequency.
- fs
- Motional series-resonant frequency (Hz)
- Lm, Cm
- Equivalent motional inductance (H) and capacitance (F)
Single-mode small-signal equivalent circuit. Equivalent elements are not literal coils and capacitors inside the package.
Explore the model
- Find the two electrodes on the quartz plate.
- Trace each support lead to a separate feedthrough.
- Observe the gap between the resonator and the cover.
From geometry to engineering
A working oscillator requires a specified crystal cut, load capacitance, drive level and amplifier circuit, followed by startup and stability measurements.