High-Efficiency Wireless Transmitters Employing RF Pulse-Width Modulation

采用RF脉冲宽度调制的高效无线发射机近几十年来，蜂窝电话和无线局域网(WLAN)等无线系统基础设施的增长，以及通信设备的广泛使用，对现代生活的多个方面产生了深远的影响。这方面的例子包括商业、娱乐、医疗保健、导航、安全和安保、社交媒体、交通和工作空间生产力，以及基本的个人对个人交流。在可预见的未来，物联网驱动的应用的出现将对无线基础设施提出更大的要求。在物联网的驱动下，更多的设备(如家用电器和工业用具)将需要无线连接。通信链路的功率效率，以及与实现小型化和低成本部署的先进半导体工艺等技术的兼容性，将对未来无线系统的扩散至关重要。效率在移动和固定设备中都很重要，以最大限度地减少能源浪费。随着未来几年可能部署数十亿台无线通信设备，对高效运营的需求实际上是根本的。能效在移动设备中也很重要，因为它直接影响设备的可用运行时间。这项拟议的研究将研究通过利用先进的互补金属“氧化物”半导体(CMOS)工艺的创新架构显著提高无线通信发射机效率的设计技术。这项研究还将包括调查可轻松重新配置以在不同终端环境中运行的发射机架构，以及减少发射机产生的杂散干扰的技术，这些杂散干扰会降低其他设备的性能。拟议研究的一个关键部分将是研究脉宽调制(PWM)信令方案，将其应用于无线发射机问题。将探索降低发射机频谱中噪声的技术。为了避免量化在时间域中产生的噪声，将研究模拟脉宽调制技术。将采用在所需的RF频段直接高效地产生脉宽调制的技术，而不需要频率上变频。这将有助于减少带外杂散，由于共存考虑，带外杂散可能是上转换基带PWM中的一个重要限制。将研究使用基于锁相环(PLL)的脉宽调制发生器来产生高速模拟脉宽调制。将研究如何使用高效的D类输出级在最小重新配置的情况下在宽带上驱动输出负载。这样的发射机可以是诸如信道绑定等技术的使能器，其中可以通过组合在多个频带上并发传输的数据流来将数据速率提高数倍。验证和验证所提出的电路技术的实际设计将在现代CMOS工艺中实现。一个实用的无线系统，如4G-LTE将被用于这一调查。这项工作将形成一名研究生研究人员的博士研究核心，他将获得无线发射器设计的理论、设计相关和实验方面的专业知识。

High-Efficiency Wireless Transmitters Employing RF Pulse-Width ModulationRanjit GharpureyThe growth in infrastructure for wireless systems such as cellular telephony and wireless local area networks (WLAN), and the widespread availability of communication devices, has had a profound impact on multiple aspects of modern life over the recent decades. Examples of this include commerce, entertainment, healthcare, navigation, safety and security, social-media, transportation and workspace productivity, in addition to basic person-to-person communication. In the foreseeable future, the emergence of applications driven by the "internet-of-things", wherein a significantly larger number of devices, such as household and industrial appliances, will require wireless connectivity, will place even greater demands on the wireless infrastructure. Power efficiency of communication links, and compatibility with technologies such as advanced semiconductor processes that enable miniaturization and low-cost deployment, will be critical to future proliferation of wireless systems. Efficiency is important in both mobile and stationary devices for minimizing energy wastage. With potentially billions of wireless communication devices being deployed over the coming years, the need for efficient operation is in fact, fundamental. Power efficiency is also critical in mobile devices since it directly impacts the available operating time of the device. The proposed research will investigate design techniques for significantly enhancing the efficiency of wireless communication transmitters through innovative architectures that leverage advanced Complementary Metal "Oxide" Semiconductor (CMOS) processes. The research will also include an investigation of transmitter architectures that can be easily reconfigured to operate in different end environments, and on techniques that reduce the spurious interference generated by transmitters, that can degrade the performance of other devices. A key part of the proposed research will be an investigation of Pulse-Width Modulation (PWM) signaling schemes, as applied to the problem of wireless transmitters. Techniques that reduce noise in the transmitter spectrum will be explored. To avoid the noise caused by quantization in the time-domain, analog-PWM techniques will be investigated. Techniques for efficient generation of PWM directly at the desired RF band without the need for frequency upconversion will be employed. This will help reduce the out-of-band spurs that can be a significant limitation in upconverted baseband PWM due to co-existence considerations. The use of phase-locked loop (PLL) based PWM generator, which allows for generation of high-speed analog PWM will be studied. The use of efficient class-D output stages to drive output loads over broad bandwidths with minimal reconfiguration will be investigated. Such transmitters can be an enabler for techniques such as channel-bonding, wherein data rates can be increased multiple-fold by combining data streams that are transmitted over multiple bands concurrently. A practical design to validate and verify the proposed circuit techniques will be implemented in a modern CMOS technology. A practical wireless system, such as 4G-LTE will be employed for this investigation. The work will form the core of the doctoral research of one graduate student researcher, who will gain expertise in theoretical, design-related and experimental aspects to the design of wireless transmitters.