艾博康超低抖动石英晶体振荡器介绍，Small form factors allow system designers to keep their products condensed and compact, but the reduced size comes at a performance cost compared to larger versions of the same components. For high-speed computations and operations, many applications require extremely low jitter from the reference clock. System designers evaluate the trade-offs and alternatives to search for the best combination of size and rms phase jitter performance. Some applications that use such low jitter technology include optical modules, cloud computing, networking, data storage, PCIe-5/6, 100G/200G/400G/800G Ethernet and other RF applications.

小的外形因素使系统设计师能够保持其有源晶振产品的简洁和紧凑，但与相同组件的较大版本相比，尺寸的减小会带来性能成本。对于高速计算和操作，许多应用程序需要极低的抖动参考时钟。系统设计者评估权衡和备选方案，以搜索尺寸和均方根相位抖动性能的最佳组合。一些使用如此低抖动技术包括光学模块、云计算、网络、数据存储、PCIe-5/6、100G/200G/400G/800G以太网和其他射频应用。
In 2019, Abracon released its first generation AK2 and AX3 series as part of the ClearClock™ family of ultra-low jitter quartz crystal oscillators. These third-overtone solutions were created to keep up with the demand for 100 to 200 MHz clocking solutions in small package sizes; particularly PCI Express, optical transceivers, data storage, and networking designs. Abracon ClearClock™ solutions are offered in LVPECL, LVDS, and HCSL outputs across this frequency range. 

2019年，Abracon发布了第一代AK2和AX3系列，作为ClearClock的一部分™ 的家族超低抖动石英晶体振荡器。这些第三泛音解决方案是为了跟上对小封装尺寸的100至200MHz时钟解决方案的需求；特别是PCI Express，光学收发器、数据存储和网络设计。Abracon ClearClock™ 提供了解决方案在该频率范围内的LVPECL、LVDS和HCSL输出中。

With the development of new oscillator IC technology, Abracon released the next generation of ClearClock™ oscillators: the AK2A and AK3A series. Matching the smaller footprints of the AK2 (2.5 x 2.0 mm) and AX3 (3.2 x 2.5 mm) respectively, the AK2A and AK3A series offer improved rms phase jitter performance without sacrificing their compact form factor. For example, at 156.25 MHz carrier frequency, the AK3A offers a typical RMS jitter of 72 fs for its HCSL output, improved from the AX3’s typical 113 fs RMS jitter performance over the 12kHz to 20MHz BW from the carrier.

随着新型晶体振荡器IC技术的发展，Abracon发布了下一代ClearClock™ 振荡器：AK2A和AK3A系列。匹配AK2的较小占地面积（2.5x2.0毫米）和AX3（3.2x2.5毫米），AK2A和AK3A系列提供了改进的均方根相位抖动性能，而不牺牲其紧凑的外形因素。例如，在156.25MHz载波频率，AK3A的HCSL输出提供了典型的72 fs的RMS抖动，比AX3的有所改进载波在12kHz到20MHz带宽上的典型113 fs RMS抖动性能.

Taking a closer look at this example, the AK3A has a 3.2 x 2.5 mm footprint and delivers 72 fs typical RMS jitter over an offset bandwidth of 12 kHz – 20 MHz (referenced from the carrier frequency), with a maximum specification limit of 100 fs. RMS phase jitter is a time domain parameter that is derived from the phase noise (frequency domain) measurement. Figures 1 and 2 show the phase noise plots of the corresponding AK3A and AX3 part numbers (AK3AHAQ1-156.25MHZ and AX3HAQ1-156.25MHZ). Both parts are operated at 3.3V with a 156.25 MHz differential HCSL output. Note that at frequency offsets starting at 100kHz, the AK3A has a lower phase noise floor than the AX3, reaching -161 dBc/Hz at a 20MHz offset.

仔细看一下这个例子，AK3A的占地面积为3.2x2.5毫米，通常可提供72 fs偏移带宽为12kHz–20MHz（参考载波频率）的RMS抖动最大规格限制为100 fs。RMS相位抖动是一个时域参数，从相位噪声（频域）测量。图1和图2显示了相应的AK3A和AX3零件号（AK3AHAQ1-156.25MHZ和AX3HAQ1-156.25MHZ）部件在3.3V下操作，具有156.25MHz差分HCSL输出。请注意，在频率偏移处从100kHz开始，AK3A的本底相位噪声低于AX3，在20MHz偏移。

The difference in phase noise is more pronounced in Figure 3, which places both phase noise graphs on the same plot. The AK3A’s lower phase noise plot results in the improvement in RMS phase jitter (12kHz - 20MHz). AK3A solutions are ideally suited for end-applications requiring 100 fs maximum rms jitter performance.

相位噪声的差异在图3中更为明显，图3中放置了两个相位噪声图在同一个地块上。AK3A较低的相位噪声图改善了RMS相位抖动（12kHz-20MHz）。AK3A解决方案非常适合要求最大rms为100fs的终端应用抖动性能。艾博康超低抖动石英晶体振荡器介绍.

Abracon’s ClearClock™ oscillator series are available in multiple output logic types, including HCSL, LVDS, and LVPECL. The AK3A example above depicts the performance with HCSL output.

Abracon晶振的ClearClock™ 振荡器系列可用于多种输出逻辑类型，LVDS和LVPECL。上面的AK3A示例描述了HCSL输出的性能。
Similarly, significant rms jitter improvement is achieved with the AK2A series compared to firstgeneration counterpart [AK2]. Figures 4 and 5 show the differences between the AK2A and AK2 series at 100 MHz (LVDS output). 

类似地，与第一代产品[AK2]相比，AK2A系列实现了显著的均方根抖动改善。图4和图5显示了AK2A和AK2系列之间的差异在100MHz（LVDS输出）。

Similar to AK3A, the improvement in phase noise performance is more evident when observing the differences in measurement floors at a 12 kHz to 20 MHz offset from the carrier frequency, as shown in Figure 6.

与AK3A类似，当观察从载波频率偏移12 kHz到20 MHz时的测量基底的差异，如图6。

Specific RMS phase jitter performance for all parts discussed above is outlined in Tables 3 and 4. It should be noted that the phase noise performance will differ with carrier frequency, supply voltage, package size, and output logic. The percentage improvement in tables 3 and 4 clearly depict the significant improvement in rms jitter performance, as the ClearClock™ series evolved from generation-I to generation-II.

表3和表4概述了上述所有部件的特定RMS相位抖动性能。它相位噪声性能将随载波频率、电源电压等而不同，封装大小和输出逻辑。表3和表4中的百分比改进清楚地说明了有效值抖动性能显著提高，如ClearClock™ 从第一代进化而来的系列到第二代。

The AK2A and AK3A utilize the next-gen oscillator ASIC, ensuring ultra-low rms jitter performance at a slight cost to power consumption. With the maximum current consumption increasing from 50 mA (Gen I) to 60 mA (Gen II), the second generation ClearClock™ oscillators are prime candidates for achieving ultra-low-rms-jitter while maintaining low power consumption.

AK2A和AK3A采用下一代振荡器ASIC，确保在功耗成本很低。最大电流消耗从50 mA（GenI） 至60毫安（第二代），第二代ClearClock™ 振荡器是实现超低均方根抖动，同时保持低功耗。