A Piezoelectric Quartz Crystal Unit is an electronic component used in frequency control applications. Piezoelectric Quartz Crystal Units are usually called “crystals.” The crystal oscillator consists of a quartz resonator equipped with electrodes, housed in a hermetically sealed package that provides some means of connection to a circuit. A crystal oscillator is an electronic oscillator that makes use of crystal as a frequency selective element to obtain an inverse piezoelectric effect. It makes use of the mechanical resonance of the vibrating crystal, which has piezoelectric properties, in order to obtain an electric signal with a high-precision frequency.
Load capacitance(CL)
Load capacitance is defined as being the total capacitance present in an oscillator circuit as measured or calculated across the pins of the crystal socket. Load capacitance has the effect of increasing the frequency of a crystal unit.
Drive Level(DL)
Exceeding the maximum drive level (power dissipation) of a crystal can lead to an increased rate of aging, Drive Level Dependency (DLD) problems, increased number and intensity of activity dips that can stop oscillation and, at very high drive levels, breakage of the crystal blank.
Pullability
Quartz crystals are not linear devices and they do not behave in a linear way. But, it is theoretically possible to achieve symmetrical pulling. Pullability is the amount by which the frequency of a crystal will change when the circuit condition is switched from series to parallel resonance. Pullability is also used to describe the frequency change that occurs when the load capacitance is switched from one value to another.
Trim Sensitivity(TS)
Trim sensitivity is the amount by which the frequency of a crystal oscillating with a specific value of load capacitance will vary if that load capacitance is varied slightly about its nominal value.
Shunt Capacitance (C0)
The shunt capacitance (C0) is the capacitance resulting from the presence of the electrodes on the quartz plate plus the capacitance inherent in the crystal holder.The motional capacitance is a parameter of the equivalent circuit. It is used as a means of describing the elasticity or “stiffness” of the quartz resonator.
Spurs
Spurs are frequency responses higher in frequency than the main response but not as high in frequency as the next regular overtone.The word “spur” is used as an abbreviation of the word “spurious” but the frequencies described by either of the two are not “spurious” at all. They are regularly occurring natural frequency responses, the amplitude of which is subject to some degree of control through crystal unit design.
About the operating temperature range
We do not recommend that you operate a crystal outside of its specified temperature range. The most notable change will be a greater frequency drift due to the increased temperature extremes. Another and more serious problem that can occur is that its activity might be weakened. The weakening activity can cause the oscillator to stop oscillating at a specific temperature.
