Design and Analysis of High-Stability THz Molecular Clock System
Name
Kim-minahkim-PhD-EECS-2022-thesis.pdf
Description
Thesis PDF
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9.05 MB
Format
Adobe PDF
Checksum (MD5)
d7eb4189814db247a2a16309eedde908
Author(s)
Kim, Minah
Advisor(s)
Han, Ruonan
Lee, Hae-Seung
Date Issued
September 2022
Publisher
Massachusetts Institute of Technology
Abstract
Miniaturized frequency references with high stability are crucial for applications such as navigation and wireless networking. Recently, chip-scale molecular clocks (CSMCs) have achieved excellent stability performance by using a rotational-mode transition of gaseous carbonyl sulfide (¹⁶O¹²C³²S). Its low-cost implementation and robustness against external electrical/magnetic fields make a CSMC an attractive candidate for a high-stability clock. However, even though an invariant OCS transition frequency is used as the reference, non-idealities such as tilted baseline of spectroscopic probing and input offsets of dc amplifiers lead to the frequency error between the actual transition frequency (𝑓₀) and the detected transition frequency. Since these nonidealities are susceptible to environmental variations, it affects the long-term stability of the clock. In addition, the short-term stability of a CSMC is limited by the spectroscopic signal-to-noise ratio.
In this work, the effects of noise and environmental variations on clock stability were analyzed to provide guidance for the design and optimization of CSMCs. Also, a dual-loop CSMC is demonstrated to address the issues in the previous CSMCs and further improve stability performance. The prototype chip implemented in 65nm CMOS technology achieves 2 ×10⁻¹¹ Allan Deviation at 10,000-s averaging time with 71-mW power consumption. It demonstrates that CSMCs can provide outstanding stability performance while maintaining cost, complexity, and power consumption advantages.
MIT Department
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
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