Exploration of SiGe HBTs for power amplifiers in the 200 GHz to 500 GHz frequency range

对毫米波和亚毫米波应用的持续增长的需求，通信、成像和感测在带宽、输出功率和能量效率方面对相应的电子系统提出了重大挑战。这种系统中的一个重要部件是功率放大器（PA），它也是能量耗散的主要贡献者。根据目前的趋势，未来更高的带宽将通过移动到更高的载波频率（比目前的5G系统中的载波频率）来实现，其中有源天线相控阵列包含数百个用于波束转向的PA和大量的多输入多输出信号。这种高度集成的高频（HF）系统只能用硅锗（SiGe）BiCMOS技术来实现。因此，探索现有的SiGe异质结双极晶体管（HBT）的能力和未来的性能要求，以实现具有足够的输出功率和高功率和频谱效率的高频功率放大器是非常感兴趣的。到目前为止，很少关注200 GHz及以上的频率，这些频率是相关的，例如，用于处理器到处理器通信、皮科和毫微微小区环境中的高数据速率传输和安全筛选，以及用于生物探测和医学成像。在这样的频率下的主要挑战是产生足够的输出功率，同时还实现高效率。 因此，拟议的项目旨在（i）探索SiGe HBT功率放大器在200…500 GHz的范围和性能限制相关的设备物理实验数据和ITRS/IRDS预测的基础上;（ii）输出功率，效率，增益，带宽和线性度之间的权衡的调查;（iii）根据混合模式数值装置仿真（TCAD），精确地对功率放大器操作期间的非线性瞬变和物理效应进行大信号紧凑型HBT建模和详细分析和制造的电路;（iv）单独评估PA在非线性大信号操作期间产生的谐波功率，例如，模型验证拟议的工作，详细介绍了三个定义明确的工作包，包括设计，制造和实验特性的导电角PA及其积木。到目前为止，在HF PA设计中实现高输出功率和效率一直受到保守方法的限制，这是由于缺乏对HBT操作限制和相应准确模型的更深入了解。现有的障碍将克服推动晶体管的操作，其物理极限，并通过仔细PA优化，考虑所有可能的器件布局选择的基础上几何可扩展的HBT建模和重要的分布式效应，如热和衬底耦合。

The continuously increasing demand for mm- and sub-mm-wave applications in, e.g., communications, imaging and sensing poses significant challenges for the corresponding electronic systems in terms of bandwidth, output power, and energy efficiency. An important component in such systems is the power amplifier (PA), which is also a major contributor of energy dissipation. According to present trends, higher bandwidth in future will be achieved by moving to much higher carrier frequencies (than those in present 5G systems) with active antenna phased arrays containing hundreds of PAs for beam steering and massive multiple-input-multiple-output signals. Such highly-integrated high-frequency (HF) systems can only be realized with silicon-germanium (SiGe) BiCMOS technology. Hence, the exploration of both the capability of existing and the requirements for future performance of SiGe heterojunction bipolar transistors (HBTs) with respect to the realization of HF PAs with sufficient output power and high power and spectral efficiency is of great interest. So far, little attention has been paid to frequencies at and beyond 200 GHz, which are relevant, e.g., for high data-rate transmission in processor-to-processor communications, pico- and femto-cell environments, and security screening as well as for biological probing and medical imaging. A major challenge at such frequencies is the generation of sufficient output power, while achieving at the same time also high efficiency. The proposed project therefore aims at (i) the exploration of the maximum achievable power density of SiGe HBT PAs operating in the 200...500 GHz range and the performance limitations related to device physics based on experimental data and ITRS/IRDS predictions; (ii) the investigation of the trade-offs between output power, efficiency, gain, bandwidth, and linearity; (iii) accurate large-signal compact HBT modeling and detailed analysis of non-linear transients and physical effects during PA operation based on mixed-mode numerical device simulation (TCAD) and fabricated circuits; (iv) separate assessment of the harmonic power generated in PAs during nonlinear large-signal operation for, e.g., model verification. The proposed work, as detailed in three well-defined work packages, includes the design, fabrication and experimental characterization of conduction-angle PAs and their building blocks. So far, achieving high output power and efficiency in HF PA designs has been constrained, among others, by conservative approaches due to the lack of deeper insight into HBT operation limits and the corresponding accurate models. The existing barriers will be overcome by pushing transistor operation to its physical limits and by careful PA optimization, considering all possible device layout options based on geometry scalable HBT modeling and important distributed effects such as thermal and substrate coupling.