Fully Integrated Parametric Filters for Extensive Phase-Noise Reduction in Low-Power RF Front-Ends and Resonant Sensing Platforms

许多手持式医疗设备和其他消费产品依赖于外差或超外差接收器进行无线连接。这种无线节点所能达到的最大数据速率在很大程度上取决于为频率转换阶段产生参考信号的内部振荡器的频率稳定性。此外，研究人员还致力于开发集成闭环谐振传感平台，该平台依靠可靠的振荡器来跟踪暴露于目标物理或化学信号时低功耗微纳米机械结构中引起的谐振频移。虽然这种小型化的谐振传感器具有实现前所未有的灵敏度的潜力，但它们的检测能力受到用作频率读出的振荡器的稳定性的强烈限制。该研究计划旨在开发新技术，以实现低功率和高频集成振荡器前所未有的频率稳定性水平，解决目前限制射频接收器和谐振传感平台性能的最关键挑战之一。特别是，提出的研究需要开发一类新的集成固态低功耗稳定电路，称为参数滤波器。这些集成电路利用参数系统的复杂非线性动力学来实现滤波器的相位噪声降低的独特功能。通过提高频率源的稳定性，所提出的参数滤波器将降低部署在物联网（IoT）应用中的电池供电无线传感器节点的功耗。此外，谐振传感平台的频率读出中的剧烈相位噪声降低将允许超越最先进的谐振传感器的分辨率限制，从而实现前所未有的检测能力。参数滤波器由一个非自治反馈网络组成，其中包括一个无源参数分频器。当一个参数滤波器被设计为在参数分频器的边缘稳定点附近工作时，它表现出松弛时间的增加，使其不受驱动信号的快速相位波动的影响。结果，参数滤波器的输出信号表现出比输入信号低几个数量级的相位噪声。该项目的一个目标是开发新型集成参数滤波器，可以连接到千兆赫频率发生器的输出端。为了演示这一概念，将设计一个2.4 GHz频率发生器和辅助电路，其总功耗低于0.6 mW。通过使用新的参数滤波器架构，预计在2.4 GHz载波的1 MHz偏移处，相位噪声将改善超过30 dB。此外，本研究的一个基本目标是开发一种系统的设计和仿真方法，允许操纵集成无源参数电路的稳定性。特别是，开发用于低功率相位降噪的参数滤波器的努力将为理解参数驱动电路元件的行为及其操纵非自治反馈网络动态的能力提供手段。此外，该项目将使用商业电路模拟器来捕捉这种复杂的动态，这将极大地有利于研究界和工业界的电路设计师。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。

Numerous handheld medical devices and other consumer products rely on homodyne or super-heterodyne receivers for wireless connectivity. The maximum data rate achievable by such wireless nodes depends heavily on the frequency stability of the internal oscillators that generate the reference signals for the frequency conversion stages. Furthermore, significant research efforts have been directed towards the development of integrated closed-loop resonant sensing platforms, which rely on reliable oscillators to track the resonance frequency shifts induced in low-power micro and nano mechanical structures upon exposure to targeted physical or chemical signals. While such miniaturized resonant sensors have the potential to achieve unprecedented sensitivities, their detection capability is strongly limited by the stability of the oscillator employed as frequency readout. This research program aims to develop new techniques to achieve an unprecedented level of frequency stability in low-power and high-frequency integrated oscillators, addressing one of the most critical challenges that is currently limiting the performance of RF receivers and resonant sensing platforms. In particular, the proposed research entails the development of a new class of integrated solid-state low-power stabilization circuits, referred to as parametric filters. These integrated circuits exploit the complex nonlinear dynamics of parametric systems to implement the unique functionality of a filter for the phase noise reduction. By increasing the stability of frequency sources, the proposed parametric filter will allow to reduce the power consumption of battery-operated wireless sensor nodes deployed for Internet-of-Things (IoT) applications. In addition, the drastic phase noise reduction in the frequency readout of resonant sensing platforms will allow to surpass the resolution limits of state-of-the-art resonant sensors, leading to unprecedented detection capabilities. A parametric filter consists of a non-autonomous feedback network that includes a passive parametric frequency divider. When a parametric filter is designed to operate in proximity to a point of marginal stability for the parametric frequency divider, it exhibits an increase in relaxation time that renders it immune to the rapid phase fluctuations of its driving signal. As a result, the output signal of parametric filters exhibit orders of magnitude lower phase noise than their input signals. An aim of this project is to develop novel integrated parametric filters that can be connected at the output of gigahertz frequency generators. To demonstrate this concept, a 2.4 GHz frequency generator and the auxiliary circuits will be designed with an overall power consumption less than 0.6 mW. Phase noise improvements exceeding 30 dB at 1 MHz offset from the 2.4 GHz carrier are expected through the use of the new parametric filter architecture. Furthermore, a fundamental goal of this research is to develop a systematic design and simulation approach that allows to manipulate the stability of integrated passive parametric circuits. In particular, the efforts to develop parametric filters for low-power phase-noise reduction will provide means to understand the behavior of parametrically driven circuit components and their capability to manipulate the dynamics of non-autonomous feedback networks. In addition, the project will use commercial circuit simulators to capture such complex dynamics, which will greatly benefit circuit designers in the research community and industry.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.