Low Noise, Tunable Non-Reciprocal RF Front-Ends Based on Time-Varying Transmission Lines (TVTL)

提出了一种有效介电特性在空间和时间上调制的传输线结构。这样的传输线支持在同一结构上的电磁波的双向传播，同时通过仅移动与时空调制的方向一致的波的频率来保持向不同方向传播的电磁波是可分离的。利用射频电路的基础科学和现代半导体技术，建议的概念将通过创造能够实现敏感和抗干扰的无线前端的新型射频设备和功能块，在现代无线系统中找到广泛的应用。这项拟议的工作促进了多个工程研究领域之间的互动。如果成功，它将彻底改变目前在充满挑战的环境中发送和接收电磁波的方式，并导致低功耗、高性能、紧凑和负担得起的下一代通信或传感器电子产品。随着移动通信技术的进步正在改变人们的生活方式，高性能的无线射频前端将为这一变化提供强大的推动力。该提议旨在通过开发可调、非互易、频率可调且噪声低的前端来解决射频前端中的噪声和干扰问题，这些问题从根本上限制了无线系统的性能。这样的前端只有通过利用时变传输线的独特性质才能实现。时变传输线由无源传输线组成，其电感或电容受另一个电磁波的时空调制。它具有无源电路和有源电路的混合特性。首先，它是一种可以设计和设计的传输线，在两个方向上都具有准确的阻抗、相位和延迟特性。此外，它还提供有源电路的功能，如放大和变频。根据这一新概念创造的设备包括具有精确控制的共振频率的谐振器，同时允许不同频率的共振耦合。这一特性可用于创建低噪声、高品质因数、可调滤波能力，即使在小型化尺寸内也是如此。这项拟议的工作将首先建立一个系统的理论，即时变传输线被用作在射频前端实现卓越性能的关键构件。这包括各种新开发的功能块，如环行器、具有参数增强的品质因数的可调谐滤波器、低噪声放大器、有源频率转换和移相电路。然后，将利用现代半导体技术对建议的设备进行芯片上集成。基于这些集成电路原型，将推导出射频前端实际实现的性能界限。最终，将探索充分利用这些设备的独特功能的新的无线系统架构和应用程序，以满足新兴的无线通信需求。

A transmission line structure with its effective dielectric property modulated in space and time is proposed. Such a transmission line supports two-way propagation of electromagnetic waves on the same structure while keeping the electromagnetic waves propagating toward different directions separatable by shifting only the frequency of the wave that aligns with the direction of the space-time modulation. Leveraging both on the fundamental science of radio frequency circuits and the modern semiconductor technology, the proposed concept will find a broad range of applications in modern wireless systems by creating novel radio frequency devices and functional blocks that enables sensitive and interference resilient wireless front-ends. The proposed work fosters interactions among multiple engineering research fields. If successful, it will revolutionize the current way of transmitting and receiving electromagnetic waves in a challenging environment and lead to next generation communication or sensor electronics that are of low power consumption, high performance, compact and affordable. As the advancement of mobile communication technology is changing human lifestyle, a high performance wireless radio frequency front-end will provide a great thrust to this change.This proposal is to attack the noise and interference issues in the radio frequency front-end that fundamentally limits of the performance of a wireless system, by developing tunable, non-reciprocal front-ends with broad frequency tunability yet low noise. Such a front-end is only enabled through exploiting the unique property of Time-Varying Transmission Line. Time-varying transmission line consists of passive transmission lines whose inductance or capacitance is space-time modulated by another electromagnetic wave. It possesses a mixture of passive and active circuit characteristics. First, it is a transmission line that can be engineered and designed to have accurate impedance, phase and delay characteristics in both directions. Furthermore, it offers functions of active circuits such as amplifications and frequency conversions. Devices created out of this novel concept include resonators with accurately controlled resonating frequency yet allowing resonances across different frequencies to couple. This property can be utilized to create low noise, high-quality factor, tunable filtering capability even within miniaturized dimensions. The proposed effort will first establish a systematic theory of Time-Varying Transmission Line being used as a key building block to achieve superior performance in radio frequency front-ends. This includes various novel developments of functional blocks such as circulators, tunable filters with parametrically enhanced quality factors, low noise amplifiers, active frequency conversion and phase shifting circuits. Modern semiconductor technology will then be utilized for on-chip integration of the proposed devices. The performance bound on practical implementations of the radio frequency front-end will be derived based on these integrated circuit prototypes. Ultimately, new wireless system architectures and applications that fully leverage on the unique features of these devices will be explored for the purpose of meeting the need of emerging wireless communications.