Cardinal低抖动晶体振荡器详情

Cardinal低抖动晶体振荡器详情，Cardinal投资于石英晶体技术，为那些需要频率控制设备的用户提供最新的大批量产品。Cardinal成立了合资企业和子公司，以提供最高频率、最高质量的零件。随着持续不断变化的市场需求增长，Cardinal公司利用自身的优势，在市场之中找到自身新的定位，并通过优化与迭代自身的石英晶振产品，从而形成独特的差异化，在产品性能与品质方面，以高于用户满意度为最大的标准，使得用户更加乐于与之建立良好的合作关系。

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Cardinal Components已确定精确测量晶体振荡器的抖动，或低于1皮秒，是目前唯一的方法可用于测量相位噪声并计算RMS抖动。请参阅我们的应用说明“晶体振荡器低抖动应用”，以获得完整的解释。什么时候测量晶体振荡器的相位噪声，我们使用双源方法。这导致单个1Hz带宽中相位的边带测量从载体则单边带相位噪声结果为在指定频带上积分，通常为10Hz至1MHz或12kHz至20MHz，具体取决于应用程序。SONET要求的带宽为12千赫至20兆赫。此频域集成相位噪声，单位为dBc/Hz，然后转换为时间
域RMS抖动（皮秒）。
在Cardinal Components非PLL振荡器中，RMS抖动具有随机高斯分布，因为不使用锁相环。结果在缺乏离散杂散和多模态的情况下非高斯分布。因此，几乎没有低噪声供电时的确定抖动电源。当抖动具有高斯时响应，RMS抖动是标准偏差或西格玛值。
Cardinal组件中使用的石英晶体振荡器具有非常高的Q值。加载的Q振荡器谐振器环路的超过100000。当振荡器级产生信号，频率可以位于振荡带宽。然而，对于高Q谐振器实现窄的振荡带宽，振荡器可以制造出具有非常低抖动的。
具有基数抖动的高斯分布分量振荡器，周期的平均值位于高斯曲线的中心。标准偏差（1西格玛）定义为
包含发生的总振荡的68.26%。这窗户放在中间的一边。1西格玛（标准偏差）值是振荡器输出信号。作为标准的编号偏离均值增加产生该周期偏差信号的振荡器是大大减少。在14.069西格玛时，概率为1:1012.FIBRE通道规范要求14西格玛可靠性.

这被认为是我们用来确定的标准从RMS抖动值的Pk到Pk抖动。如果红衣主教分量振荡器具有2皮秒RMS抖动，Pk到Pk的抖动是28皮秒。这也是被认为是总抖动（TJ）。

下图显示了其他所需的西格玛偏差各种可能性：
概率西格玛

1:108 11.224 

1:109 11.996 1:1010 12.723 1:1011 13.412 

1:1012 14.069 1:1013 14.698 1:1014 15.301 

1:1015 15.883 1:1016 16.444

Cardinal Components has determined that to accurately measure jitter of crystal oscillators, at or below 1 pico-second, the only method presently available is to measure phase noise and calculate RMS jitter. See our application note “Crystal Oscillators for Low Jitter Applications” for a full explanation. When measuring the phase noise of crystal oscillators, we use the two source method. This results in a single sideband measurement of phase in a 1 Hz bandwidth over a specific range of offset frequencies from the carrier. The single side band phase noise result is then integrated over a specified band of frequencies, usually 10 Hz to 1 MHz or 12 kHz to 20 MHz depending on the application. The SONET requirement bandwidth is 12 kHz to 20 MHz. This frequency domain integrated phase noise, in dBc/Hz, is then converted into a time domain RMS jitter in picoseconds.

In Cardinal Components non-PLL oscillators, the RMS jitter has a random Gaussian distribution, because there are no phase locks loops used. This results in the lack of discrete spurious and multimodal non-Gaussian distribution. Hence, there is little or no deterministic jitter when powered by a low noise power supply. When the jitter has a Gaussian response, the RMS jitter is the standard deviation or one sigma value.

The crystals used in the Cardinal Components oscillators have a very high Q value. The loaded Q of the oscillator resonator loop is between 10,000 to over 100,000. When the oscillator stage generates the signal, the frequency can reside anywhere within the oscillating bandwidth. However, with high Q resonators achieving a narrow oscillation bandwidth, oscillators with very low jitter can be manufactured. 

With the Gaussian distribution of jitter of the Cardinal Components oscillators, the Mean value of the period is in the center of the Gaussian curve. Standard Deviation (1 sigma) is defined as the window that contains 68.26% of the total oscillation that occurs. This window is placed on one side of the mean. The 1 sigma (Standard Deviation) value is the RMS jitter of the oscillator output signal. As the number of Standard Deviations increases from the Mean, the chance of the oscillator producing a signal of that period deviation is greatly reduced. At 14.069 sigma, the probability is 1:1012. FIBRE Channel specifications requires 14 sigma reliability.

Determining the Peak to Peak (Pk to Pk) value depends on the reliability that is desired. The more reliability desired, the greater the Pk to Pk value even though the probability of occurrences greatly reduces with higher sigma values. At 14 sigma, the probability is near 1:1012 . This is considered the standard we use to determine the Pk to Pk jitter from the RMS jitter value. If a Cardinal Components oscillator has a 2 picoseconds RMS jitter, the Pk to Pk jitter is 28 picoseconds. This is also considered the Total Jitter (TJ) .