CAREER: Analog-Assisted Transceivers for Next-Generation Millimeter-Wave Systems

在增加无线电频谱接入需求的推动下，商业和国家安全系统越来越多地转向毫米波载波频率。除了减小物理尺寸和重量外，这种频率调整还具有优势，因为它支持更高带宽的信号，进而产生更高的数据速率。然而，在系统一级，频率缩放是有问题的，因为大多数无线电系统中使用数字信号处理元件来产生信号并对其进行操作。随着信号带宽的增加，数字信号处理所需的时钟频率也会增加，从而导致更多的功耗和性能下降。因此，成功地扩展到毫米波频率需要具有宽带信号处理替代解决方案的新颖无线电架构。为了解决这个问题，该项目研究了工作在毫米波电路领域的线性和非线性模拟技术，以显著改善下一代无线系统的信号处理。由此产生的模拟辅助架构将满足高性能无线系统至关重要的领域的需求，例如通信、物联网、自动驾驶车辆和医疗保健应用。这些技术将作为模块纳入首席研究员的教育目标，重点放在无线电实验上，主题从系统级到部件级。首席研究员将与科罗拉多博尔德大学现有的大学预科和工程预科项目合作，作为一种吸引代表不足的第一代大学生参与工程的方式。这项研究的目标是系统地调查模拟信号处理和经典控制技术在采用宽带隙器件技术的宽带毫米波(mm波)系统中的应用。缩放的基本原理表明，模拟技术在毫米波系统中变得越来越有吸引力，因为在高载波频率下，即使瞬时带宽急剧增加，模拟技术的分数带宽也相对较低。因此，来自模拟电路设计和经典控制理论的技术将被用作补偿数字域带宽限制的一种方式。提出了一种体系结构研究，以分析当带宽和功率是主要资源时，数字/射频(RF)域边界对功耗、复杂度和大小的影响。一个特别的焦点将是负载调制功率放大器的非线性分析，作为效率增强型发射机中数字/射频接口设计的目标驱动器。实现模拟辅助体系结构将反过来需要组件级的新支持电路。为此，该研究将利用GaN技术的高跨导和转换频率，开发模拟和混合模式电路。所提出的技术包括用于例如基于偏置的增益校正的集成低频控制路径，以及开发用于信号产生和控制的基本构建块。为了验证本文提出的设计方法，这些技术的演示将是一款内置线性校正的新型宽带收发信机。通过这一研究项目，线性和高效宽带毫米波系统的性能将得到显著改善，使电磁频谱能够得到新的和创新的使用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Driven by the need for increased radio spectral access, commercial and national security systems are increasingly moving to millimeter-wave carrier frequencies. In addition to reducing physical size and weight, this frequency scaling is beneficial because it enables higher-bandwidth signals which, in turn, produce higher data rates. At the system level, however, frequency scaling is problematic because of the digital signal processing elements used in the majority of radio systems to generate and operate on signals. As the signal bandwidth is increased, the clock rate required for digital signal processing is also increased, leading to more power consumption and performance degradation. Successfully expanding to millimeter-wave frequencies therefore requires novel radio architectures with alternative solutions for broadband signal processing. To address this issue, the project investigates both linear and nonlinear analog techniques, operating in the millimeter-wave circuit domain, to substantially improve the signal processing of next-generation wireless systems. The resulting analog-assisted architectures will address the needs in areas where high-performance wireless systems are critical, such as communications, internet of things, autonomous vehicles, and healthcare applications. These technologies will be incorporated into the principal investigator's educational goals as modules with focus on experimentation with radios, with topics ranging from system to component level. The principal investigator will partner with established pre-collegiate and pre-engineering programs at the University of Colorado Boulder as a way to engage underrepresented and first-generation college students in engineering.The goal of this research is to systematically investigate the application of analog signal processing and classical control techniques to wideband millimeter-wave (mm-wave) systems employing wide-bandgap device technologies. Fundamental principles of scaling indicate that analog techniques become increasingly attractive in mm-wave systems due to the relatively low fractional bandwidths at high carrier frequencies even when instantaneous bandwidths increase dramatically. Techniques from analog circuit design and classical control theory will therefore be leveraged as a way to compensate for digital-domain bandwidth limitations. An architecture study is proposed to analyze the impact of the digital / radio-frequency (RF) domain boundary on power consumption, complexity, and size when bandwidth and power are prime resources. A specific focus will be the nonlinear analysis of load-modulated power amplifiers as a targeted driver of this digital / RF interface design in efficiency-enhanced transmitters. Realizing analog-assisted architectures will, in turn, require novel supporting circuits at the component level. To this end, the research will develop analog and mixed-mode circuits in GaN technology, leveraging its high transconductance and transition frequency. Proposed techniques include integrated low-frequency control paths for, e.g., bias-based gain correction, and developing fundamental building blocks for signal generation and control. To validate the design methodologies developed in this work, the demonstration of these technologies will be a novel wideband transceiver with built-in linearity correction. Through this research project, the performance of linear and efficient wideband mm-wave systems will be substantially improved, enabling new and innovative uses of the electromagnetic spectrum.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.