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- [技术支持]Fortiming晶体谐振器XCS21-26M000-1E10C10的基本技术2024年04月16日 23:07
Fortiming晶体谐振器XCS21-26M000-1E10C10的基本技术 石英晶体谐振器（通常称为“晶体”）因其无与伦比的高Q值、稳定性、小尺寸和低成本组合而广泛用于频率控制应用。已经研究了许多不同的物质作为可能的谐振器材料，但是多年来，石英谐振器在满足精确频率控制的需求方面一直是优选的。与其他谐振器相比，例如LC电路、音叉之类的机械谐振器以及基于压电陶瓷谐振器或其他单晶材料的谐振器，石英谐振器具有独特的综合性能。 首先，单晶石英的材料特性在时间、温度和其他环境变化下极其稳定，并且从一个样本到另一个样本具有高度可重复性。石英的声学损耗或内部摩擦非常低，这直接导致石英谐振器的关键特性之一，即其极高的Q因子。石英的本征Q值约为1071兆赫时。安装的谐振器通常具有几万到几十万的Q因子，比最好的LC电路好几个数量级。 - 阅读（895）
- [公司新闻]Introduction to FOX Crystal Oscillator Company2023年10月08日 09:29
- Founded in 1979, FOXcrystal is a small, family-owned company that provides quartz crystal resonators and oscillators. Since then, the company has grown to become a leading supplier of high-precision quartz crystal oscillators, high-reliability frequency control products for the U.S. electronics market, with more than 10,000 customers worldwide. The R&D department has been an important driver of the company's sustained growth over the past 32 years. Fox engineers have developed hundreds of products that set new standards for crystal and oscillator performance, accuracy and reliability, and to shorten lead times to meet growing business demands. Fox prides itself on being at the forefront of frequency control technology and continues to develop new products with quality company research. With state-of-the-art manufacturing facilities, including state-of-the-art equipment operating under atmospheric conditions, including the Class-100 clean room, Fox Electronics is able to produce innovative products that meet the most stringent industry quality standards. In April 2012, Integrated Device Technology, Inc. Acquired Fox Electronics and returned to private ownership of Fox's longtime management team in October 2016.
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- [行业新闻]Resonators的各项参数及性能2019年11月05日 14:39
石英晶体谐振器在电子学中的重要性在于其极高的Q值、相对较小的尺寸和优异的温度稳定性。
石英晶体谐振器利用石英的压电特性直接压电效应是指机械应力作用下某些材料产生的电极化效应。逆效应是指同一材料在电场作用下产生的变形。
在石英晶体谐振器中，在两个电极之间放置一薄片石英，其相对于晶体轴以适当的方向切割。施加在这些电极上的交流电压会使石英同时振动。伴随而来的极化变化构成了通过谐振器的电位移电流。
当外加电压的频率接近石英薄片的机械共振频率之一时，振动的振幅变得很大。伴随的位移电流也会增大，因此器件的有效阻抗会减小。在石英晶体谐振器作为晶体振荡器的频率控制元件的应用中，阻抗随共振附近频率的变化而迅速变化是关键因素。
在电气方面，石英晶体可以用图1中的等效电路表示，其中串联组合r1、l1和c1表示压电效应对阻抗的贡献，c0表示电极之间的并联电容以及任何杂散保持器电容。电感l1是石英质量的函数，而电容c1与其刚度相关。电阻r1是石英和安装装置损耗的结果。等效电路的参数测量精度可达1%左右。
等效电路的电抗频率图如图2所示。晶振性能的相关公式有很多，其中第一个是fs。这是晶体串联共振的频率，由下式给出：
其中fs以赫兹表示，l1以亨利表示，c1以法拉表示。
典型晶体参数值
校准公差
校准公差是晶体在特定温度、基准温度（通常为25°C）下频率的最大允许偏差。
频率稳定性
晶振不稳定有多种原因。温度变化和质量的物理变化导致了我们称之为老化的长期漂移，这可能是我们最关心的问题。
通过适当选择晶振切割和（对于严格的公差要求）在晶振电路中包括与温度相关的电抗，或在小烤箱中保持恒定温度，可将温度变化的影响降至最低。at-cut晶体是当今应用最广泛的晶振，因为它们的频率-温度曲线家族很容易以低成本为所有应用（除了最苛刻的应用）提供良好的性能。
未补偿的AT切割晶体可以在-10°C到60°C的范围内规定公差为±5ppm，更宽的温度范围需要更大的公差，如图3所示，显示了AT切割频率温度曲线的典型系列这些曲线可以用三次方程表示，并且强烈依赖于石英坯料的切割角度零温度系数的点称为上下拐点通过选择切割角度，可以将一个转折点放置在需要的位置；然后固定另一个转折点，因为这两个转折点在20°~30°C范围内的某个点上是对称的。转弯点之间的坡度随着它们一起移动而变小。设计用于烘箱的晶体被切割，以便上转折点与烘箱工作温度一致。
图4显示了几个低频切割的频率-温度曲线。J-cut在10kHz以下使用，而XY-cut可以在3kHz到85kHz之间使用。可在10KHz范围内使用NT切割。dt-cut适用于100khz至800khz左右，ct-cut适用于300khz至900khz。
负载电容
晶振可以由其制造商在fr处进行校准，在fr处它们看起来是电阻的（或非常接近fr的fs），或者在与电容性负载共振时，它们当然必须是电感的。后一种情况称为负载共振，通常用符号fl表示；更具体地说，符号f30，例如，表示晶体与30pF电容性负载共振的频率。
晶体电抗曲线上需要校准的点由电路结构决定一般来说，振荡器中的非反相保持放大器需要在fr处校准，而反相放大器需要在“负载电容”cl的某个值处校准。后一种配置依赖于电感晶体以及与之共振的负载电容，提供180度的相位偏移。
该规则最常见的例外是，当小电容器（例如变容二极管）与非反相放大器电路中的晶体串联以提供一定程度的频率调整时。在这种情况下，必须用电容的平均值校准晶体的共振。
可拉性
晶体的可拉性是在给定的负载电容变化下测量其频率变化的一种方法。这通常表示为串联谐振频率（fr）和负载谐振频率（fL）之间的差异该偏移量可使用分数负载谐振频率偏移量（dl）以百万分之几计算，即给定值cl时，从fr到fl的实际频率变化。
其中C1，C0和CL均以相同单位表示。图5显示了频率变化相对于负载电容变化的影响的典型曲线。
另外，通常将晶体的可拉性表示为修整灵敏度，单位为ppm / pF负载电容变化。 通过ppm / pF给出：
其中C1，C0和CL以pF为单位，并且在图6中以图形方式显示了（C0 + CL）的各种值。
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- [行业新闻]Crystal parameters description2019年10月29日 10:37
About Crystal parameters description,Crystal Project Name
AT Cut Crystals
For precise frequency control in radio and line communication systems, quartz crystal resonators have proved indispensable. The material properties of crystalline quartz are such that quartz resonators display stableness and Q factors that cannot be matched by other types of resonator over the frequency range from 1 MHz to 200 MHz.
Equivalent Circuit
Fig-1 shows the conventionally accepted equivalent circuit of a crystal resonator at a frequency near its main mode of vibration. The inductance LI reiperesents the vibrating mass, the series capacitance CL the compliance of the quartz element and the resistance Rl the internal frication of the element, mechanical losses in the mounting system and acoustical losses to the surrounding environment.
The shunt capacitance Co is made up of the static capacitance between the electrodes, togettier with stray capacitances of the mounting system.
There are two zero-phase frequencies associated with this simple circuit, one is at series resonance fs, another at antiresonance fa. When used in an oscillator, crystal units will operate at any frequency within the broken lines of Fig-2 as determined by the phase of the maintaining circuit.
By changing of this reactive condition, the crystal frequency may be trimmed in a limited extent. The degree to which this frequency may be varied (frequency pulling) is inversely proportional to the capacitance ratio r(C〇 /Ci).
Load Capacitance
Many practical oscillator circuits make use of a load capacitor CL in series or parallel with the crystal, either in order to provide a means for final frequency adjustment, or perhaps for modulation or temperature compensation purposes. For the crystal load capacitance. We looking into the circuit through the two crystal terminals, the load capacitance need to specified when the crystal is paralleled mode, crystal load capacitance is calculated as below:
Frequency Pulling
In many applications a variable capacitor (trimmer) is used as the load reactive element to adjust the frequency. The fractional frequency range available between specified values of this load reactive element is called the pulling range (PR.) and it can be calculated by using the following formula:
Sensitivity
A useful parameter to the design engineer is the pulling sensitivity (S) at a specified value of load capacitance. It is defined as the incremental fractional frequency change for an incremental change in load capacitance. It is normally expressed in ppm/pF (10-6/pF) and can be calculated from the formula:
It is very important to define the mean load capacitance to enable the actual crystal frequency be set within the tolerances of the specified nominal frequency. It is also important to use, wherever possible, standard values of load capacitance; for example:20pF, 30pF.
Fig-3 shows the relationship between LO.; P.R. and S.
Frequency Pulling Calculation
An approximation to the pulling for any crystal can be calculated from this simple formula:
Resistance
The equivalent circuit of the crystal has one other important parameter: This is Ri, the motional resistance. This parameter controls the Q of the crystal unit and will define the level of oscillation in any maintaining circuit. The load resonance for a given crystal unit depends upon the load capacitance with which that unit is intended to operate. The frequency of oscillation is the same in either series or parallel connection of the load capacitance.
If the external capacitance is designated the load resonance resistance may be calculated as follows:
The equivalent shunt or parallel resistance at load resonance frequency is approximately:
It should be remembered that Ri does not change thus the effective parameters of any user network can be readily calculated.
Frequency Temperature Characteristics
The AT-cut crystal has a frequency temperature characteristic which may be described by a cubic function of temperature. This characteristic can be precisely controlled by small variations in the exact angle at which the crystal blank is cut from the original quartz bar. Fig,4 illustrates some typical cases. This cubic behaviour is in contrast to most other crystal cuts, which have parabolic temperature characteristics.
As a consequence, the AT-cut is generally the best choice when specifying a unit to operate over a wide temperature range, and is available in a range of frequencies from 1 to 200 MHz.
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- [行业新闻]TranskoCrystal石英晶振完整型号一览2018年06月12日 11:36
TranskoCrystal晶振公司是一家位于加利福尼亚洲内阿纳海姆的频率元器件制造公司.主要以振荡器模块为主要生产目标.从最初的石英晶体谐振器制作到引进高端TCXO晶振及VCXO晶振的生产设备.1993年在美国的加利福尼亚州拉古纳山开设制造工厂.以下是Transko晶振石英晶体系列型号说明.
TranskoCrystal is a frequency component manufacturing company located in Anaheim, California. It mainly uses oscillator modules as the main production target. From the initial production of quartz crystal resonators to the introduction of high-end TCXO crystal and VCXOCRYSTAL oscillator production equipment. In 1993, we opened a manufacturing plant in Laguna Hills, California, USA. The following is a description of the Transko crystal quartz crystal series.
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