石英晶体振荡器_名词解释(英文).doc

CRYSTAL UNIT TECHNICAL TERMSActivity : A term associated with the resistance of a crystal unit. A crystal unit with low resistance is said to have good activity while a crystal unit with high resistance is said to have bad activity. Activity Dip : A term used to describe a sudden increase followed by a return to the previous level of the activity of a crystal unit. Aging : A change in the frequency and/or the resistance of a quartz crystal unit with the passage of time. Angle : The angle at which a resonator plate is cut from the quartz stone in relation to the original crystallographic axes. The angle of cut is critical to the performance of the crystal unit, particularly in the area of frequency deviation over a temperature range. AT cut : The commercial designation for a specifically oriented resonator plate, having desirable and repeatable operating characteristics. The "AT cut" is the most popular thickness-shear crystal unit manufactured today. AT Strip : An AT-cut crystal in the shape of a rectangular strip. It has a higher ESR than a round AT-cut crystal but is smaller in size, thus allowing smaller crystal packages. Axis : A direction in a quartz stone. The plural of "axis" is "axes." Base : The lower portion of a crystal holder. The base incorporates a resonator mounting structure and leads or pins to connect the device to an external circuit. See also "Holder." Bevel : A modification to one or both of the major faces of a resonator plate in which the face is altered to have a partially spherical configuration. Also see "Contour." Blank : A quartz resonator plate. Also known as a "wafer," a "plate," or a "resonator." BT cut : The commercial designation for a specifically oriented resonator plate, having well known and repeatable characteristics. The "BT cut" is less popular than the "AT." C0 : The abbreviation for "Shunt Capacitance." C1 : The abbreviation for "Motional Capacitance." Motional capacitance is also often abbreviated as "Cm." Capacitance : The property exhibited by two conductors separated by a dielectric whereby an electric charge becomes stored between the conductors. Capacitance is measured in "farads" and is identified by the letter "C." Capacitor : A passive electronic circuit component consisting, in its simplest form, of two metal electrodes separated by a dielectric. Can : See "Cover" C.I : The abbreviation for "crystal impedance," sometimes used in place of the word "resistance." C.I.M : The abbreviation for "crystal impedance meter." See "Test Set" Cold Weld : Procedure in which the base and can are dissimilar metals that are pressed together to form one metal. Contour : A modification to one or both of the major faces of a resonator plate in which the face is altered to have a completely spherical configuration. Also see "Bevel." Coupled Mode : An unwanted mode that becomes energized at the same frequency as the desired mode, thereby draining energy from the desired mode. Cover : The upper portion of a crystal holder, also referred to as a "can." Also see "Holder" Crystal : A generic term used in place of the more complete expression "piezoelectric quartz crystal unit." Cycle : One complete repetition of an event. Deviation : The amount by which a quantity differs from its nominal value. For our purposes, the amount by which a frequency differs from the nominal or specified frequency. Dew Point : The temperature at which a condensible component of a gas starts to condense into a liquid. Drive Level : The amount of power dissipated by the oscillating crystal unit. Usually expressed in terms of mW. Equivalent Circuit : The equivalent circuit shown below depicts electrical activity of a quartz crystal unit operating at its natural resonant frequency. The CO, or shunt capacitance, represents the capacitance of the crystal electrodes plus the capacitance of the holder and leads. R1, C1, and L1 compose the "motional arm" of the crystal, and are referred to as the motional parameters. The motional inductance (L1) represents the vibrating mass of the crystal unit. The motional capacitance (C1) represents the elasticity of the quartz, and the resistance (R1), represents bulk losses occurring within the quartz. ESR : The abbreviation for "Equivalent Series Resistance." As a crystal unit has a resistive element, this term is required in order to define and quantify that characteristic. Etch : A process used in the manufacture of some types of crystal units. The etch process results in an improved surface condition and an increase in the frequency of a blank. The word "etch" is also used to describe the material used in the etch process, as well as the process itself. Frequency : The periodic repetition of an event within a unit of time. In an electrical circuit, the number of waves that pass a given point in one second. The number of times a resonator plate oscillates or vibrates in one second. The nominal or desired frequency specified by a customer. Frequency Stability : T。