CMOS THz Molecular Clock With Enhanced Stability And Energy Efficiency

高性能时钟提供稳定的输出参考频率，在导航、安全、无线广播、电信网络同步和各种传感应用（例如磁力计）的电子系统中至关重要。虽然可以从全球定位系统（GPS）卫星获得高精度的定时信号，但在许多情况下（例如水下、地下和某些室内条件）是不可用的。GPS授时也容易受到电磁干扰，尤其是在战时。因此，在电子系统中采用创新的高稳定性计时装置是非常重要的。由于许多电子系统是可移动的，它们的内部时钟也应该小而节能。目前，广泛使用的时钟器件，如晶体振荡器和微机电系统（MEMS）振荡器，只能在0.01 ppm到100 ppm的范围内实现稳定，这对于上述许多应用来说是不够的。为了获得更好的稳定性，用于精确计时的高端振荡器也将消耗几瓦的更高功率。另一方面，由于原子钟的输出被锁定在特定的物理常数上，因此提供了极好的稳定性。然而，这是以巨大的外形尺寸和成本为代价的。该项目提出了一种新的太赫兹（THz）分子钟来解决上述挑战。提出的新方案将在万亿分之一的范围内实现稳定，这将比目前最先进的方案好几个数量级。该结果将推动太赫兹科学和工程，并对数十亿电子系统产生重大的潜在影响。该研究将与麻省理工学院的本科和研究生教育紧密结合，以培养具有跨学科训练和视野的未来工程领导者。在这个项目中，将研究将电子输出频率与不变物理常数联系起来，但使用替代传统原子物理的物理机制的新方法。极性分子在太赫兹波探测下的旋转模式跃迁将被用作时间基。太赫兹波的产生、检测和控制将使用标准的互补金属氧化物半导体（CMOS）集成电路技术来实现。因此，这项研究有望导致具有非常小的尺寸，非常低的功耗和非常低的成本的高稳定性时钟。具体来说，将利用分子的多共振来增强分子钟的长期稳定性。为了使时钟尺寸小型化，还将采用新的封装技术。在系统级，时钟也将以低占空比的方式运行，以获得毫瓦级的功耗。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

High performance clock, which provides a stable output reference frequency, is critical in electronic systems for navigation, security, wireless broadcasting, telecommunication network synchronization, and various sensing applications (e.g. magnetometer). Although a high-precision timing signal can be obtained from Global Positioning System (GPS) satellites, it is unavailable in many scenarios (e.g., underwater, underground, and certain indoor conditions). GPS timing is also susceptible to electromagnetic interference, especially at wartime. It is therefore of great importance to have innovative high-stability time-keeping devices local to the electronic systems. Since many of the electronic systems are mobile, their internal clocks should also be small and energy efficient. At present, the widely used clock devices, such as the crystal oscillators and the microelectromechanical system (MEMS) oscillators, can only achieve stability in the range of 0.01 ppm to 100 ppm, which is inadequate for many of the above applications. Achieving much better stability, the high-end oscillators used for precision timing would also consume much higher power of several watts. On the other hand, the atomic clocks, with their outputs locked to certain physical constants, offer excellent stability. This, however, comes at the expense of exceedingly large form factor and cost. This project proposed a novel terahertz (THz) molecular clock to address the above challenges. The proposed new solution will achieve stability in the range of parts per trillion, which will be several orders better than the current state-of-the-arts. The results will advance the THz science and engineering, and have significant potential impacts on billions of electronic systems. The research will be tightly integrated with the undergraduate and graduate education at MIT to cultivate the future engineering leaders with interdisciplinary training and vision. In this project, new approaches, which link an electronic output frequency with invariant physical constant but use a physical mechanism alternative to conventional atomic physics, will be investigated. The rotational-mode transitions of polar molecules under the probing of THz waves will be utilized as time bases. The generation, detection, and control of the THz waves will be implemented using standard complementary metal-oxide-semiconductor (CMOS) integrated circuit technology. The research, therefore, is expected to lead to high-stability clocks with very small size, very little power, and very low cost. Specifically, multi-resonance of molecules will be utilized to enhance the long-term stability of the molecular clock. New packaging technology will also be applied in order to miniaturize the clock size. At the system level, the clock will also operate in a low duty-cycled manner to obtain milliwatt-level power consumption.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.