Millimeter-Wave SiGe Transceiver Components for Next Generation Communications and Radar

(Georgia Institute of Technology, 2023-04-25) Moradinia, Arya

The objective of this research is to examine circuit design methodologies to approach the challenge of designing Silicon-Germanium (SiGe) Heterojunction Bipolar (HBT) Radio-Frequency (RF) circuit components for mm-Wave frequency (30 – 300 GHz). Mm-Wave frequency is desirable for next generations communications standards such as 6G due to the greater available bandwidth enabling vastly higher data rates and radar applications such as automotive radar due to the increased spatial resolution. At mm-Wave frequency such as W-Band (75 – 110 GHz) or D-Band (110 – 170 GHz), SiGe HBT transistor gain starts to collapse as the frequency of operation approaches large fractions of the device current gain cutoff frequency (fT) and atmospheric attenuation at D-Band is several orders of magnitude greater than at sub-6 GHz. These challenges stipulate that novel circuit design techniques be utilized to enhance circuit performance at mm-Wave and massively scaled phased arrays be utilized to overcome the increased path loss at mm-Wave. Therefore, it is desirable that SiGe HBT mm-Wave circuits achieve high performance and low power consumption, compact die are to maximize the performance, form factor of mm-Wave transceivers and phased arrays, respectively.
Device Layout Techniques for RF Performance Enhancement on SiGe HBTs for Future Generation BiCMOS Technology

(Georgia Institute of Technology, 2023-04-05) Sepulveda, Nelson E.

A study of RF performance techniques and their tradeoffs for SiGe heterojunction transistor (HBT) devices was presented. Performance results metrics showed that the τTH can be reduced by up to 37%, with increased fmax (by 17%), increased 1dB compression point (P1dB) (by 9%), and higher power-added-efficiency (PAE) (by 1.3%), and increased transducer gain (by 4.7%) using only layout optimization, with only a slight degradation of 4.5% in maximum available gain (MAG), and 8% in fT. The candidate device layouts presented can assist circuit designers in mitigating thermal memory effects at the device level, thereby improving the overall linearity of power amplifiers. This work has been accepted for publication and is available online on IEEE Transactions on Electron Devices. Similarly, another technique using induced stress to engineer the bandgap and improve performance was presented. The results show that adding more dummy metal layers to the BEOL increases collector current density (JC) and base current density (JB) at most by 25% and 15%, respectively. Similarly, additional dummy metal layers reduce current gain (β) and JB stress degradation by 30% and 100%, respectively. Sentaurus TCAD was used to explain how reduced self-heating contributes more strongly to the Auger generation rate than the stress-induced bandgap modulation, thereby improving reliability. This work has been accepted for publication and presented at the IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium. Future work should be focused on how these performance enhancements will be impacted by the RF breakdown due to BEOL dummy layers. In addition, another unexplored aspect of reliability using BEOL dummy metal layers as a performance enhancement technique is operation over a wide range of temperatures and its related physics.
Broadband Silicon-Germanium Integrated Circuits for Millimeter-Wave Communications Systems

(Georgia Institute of Technology, 2022-08-18) Rao, Sunil

The objective of this research is to investigate new circuit topologies for millimeter-wave and sub-millimeter wave integrated communications systems. To overcome the high free space path loss, emerging applications at millimeter-wave and sub-millimeter wave frequencies are driving the need for highly scalable systems. These systems require sub-circuits to operate power efficiently and with low loss. In addition, for high data rate communications, the circuits must maintain their performance over wide bandwidths. To overcome these strict requirements, we investigated novel circuit topologies uniquely suited to millimeter-wave frequencies for a variety of fundamental building blocks in a millimeter-wave transceiver. The circuits include a highly efficient D-band frequency doubler, a wideband V and W-band transformer-based distributed attenuator, a high power and efficient D-band power amplifier, D-band phase shifter, and D-band SPDT switch.
Silicon-Integrated Photonics for Space Systems

(Georgia Institute of Technology, 2022-01-14) Goley, Patrick Stephen

Silicon-integrated photonics have attracted strong interest for space, defense, and basic research applications for their ability to scale the size, weight, power, and cost of optoelectronic systems. Many of these new applications involve deployment of this new technology into hazardous radiation environments, such as in geostationary orbit around the earth, or within particle accelerators, for example. The effects of radiation from high-energy particles on conventional integrated circuits have been studied for over 50 years, and this field remains very active today. Silicon photonic integrated circuits, on other hand, having been commercialized only recently, represent a far less mature technology. Consequently, radiation effects research in this field is just beginning. The objective of this research has been to methodically subject the fundamental building blocks of silicon photonic systems to different types of hazardous radiation using theoretical, computational, and experimental methods, and to systematically characterize the effects on device and circuit behavior, so that vulnerabilities may be understood, risks can be assessed, and radiation hardening methods may be devised as needed. Throughout this process special attention has been given to identifying the underlying physical mechanisms driving any observed radiation-induced changes, or behind the absence of changes, so that findings can be generalized as much as possible, with the goal of enabling broad predictive capability. Where appropriate, and when opportunities have presented themselves, this work has delved into topics beyond radiation effects and into basic device research. One such case was driven by a need for deeper understanding of material and device properties to describe a particular radiation effect. In another case, a novel silicon-integrated photodetector architecture, well suited for many space applications, is demonstrated.
MILLIMETER-WAVE QUADRATURE RECEIVERS FOR ATMOSPHERIC SENSING AND RADIOMETRY

(Georgia Institute of Technology, 2021-10-04) Frounchi, Milad

The objective of this research is to investigate the design challenges of millimeter wave (mm-wave) quadrature receivers for emerging applications and develop new ideas to ad- dress these challenges. Next-generation wireless networks, satellite communications, atmospheric sensing instruments, autonomous vehicle radars, and body scanners are targeting to operate at mm-wave frequencies, and high-performance electronics are needed to enable these technologies. In this research, we investigate novel circuit topologies to improve the performance of existing mm-wave quadrature receivers, particularly for radiometry and remote sensing applications. A transformer-based front-end switch is co- designed with an LNA where the transformer acts as the input matching network of the LNA, reducing the front-end loss and system noise figure. Broadband and low-loss quadrature signal generation networks are proposed to provide highly balanced quadrature signals to reject the image frequency content. In addition, a high-efficiency frequency multiplier topology is demonstrated, achieving superior performance compared to the state-of-the-art designs. Lastly, the reliability and noise performance of on-chip noise source devices (PN junctions) in a SiGe BiCMOS platform was characterized and compared. To confirm the advantages of our ideas, the measurement and simulation results of all fabricated circuits are presented and discussed.
NEW APPROACHES TO WIDEBAND RF SWITCHING IN SILICON-GERMANIUM TECHNOLOGY

(Georgia Institute of Technology, 2021-07-27) Cheon, Clifford DongYoung

The objective of this research is to develop and investigate radio frequency (RF) switches utilizing silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) to provide a novel design approach for next-generation wideband circuits and systems. SiGe HBTs offer relatively small parasitic capacitance, making them suitable for wideband RF switching transistors with low insertion loss. Despite the available performance, the effective utilization of SiGe HBTs as RF series switches remains largely unexplored. The research presented in this dissertation introduces a novel RF series switch architecture, namely an anti-parallel (AP) SiGe HBT pair, as a potential wideband switching element for next-generation systems. The benefits of this novel RF series switch architecture are investigated, as well as insightful optimization techniques and an analysis of its operational principles. The dissertation then provides implemented design examples and develops design techniques leveraging properties possessed by the AP SiGe HBT pair.
Using SiGe HBTs for quantum science at deep cryogenic temperatures

(Georgia Institute of Technology, 2021-02-15) Ying, Hanbin

The objective of this research is to investigate the feasibility of using BiCMOS technology for these quantum science applications and clear some major roadblocks. The requirement for these applications is detailed, and the research is conducted in a systematic way targeting four important aspects of SiGe HBTs, namely, cryogenic characterizations, device physics, compact modeling, and circuit designs.
Radio Frequency and Millimeter Wave Circuit Component Design with SiGe BiCMOS Technology

(Georgia Institute of Technology, 2020-12-06) Gong, Yunyi

The objective of this research is to study and leverage the unique properties and advantages of silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) integrated circuit technologies to better design radio frequency (RF) and millimeter wave (mm-wave) circuit components. With recent developments, the high yield and modest cost silicon-based semiconductor technologies have proven to be attractive and cost-effective alternatives to high-performance III-V technology platforms. Between SiGe bipolar complementary metal-oxide-semiconductor (BiCMOS) technology and advanced RF complementary metal-oxide-semiconductor (CMOS) technology, the fundamental device-level differences between SiGe HBTs and field-effect transistors (FETs) grant SiGe HBTs clear advantages as well as unique design concerns. The work presented in this dissertation identifies several advantages and challenges on design using SiGe HBTs and provides design examples that exploit and address these unique benefits and problems with circuit component designs using SiGe HBTs.
Characterization and Mitigation of Single-Event Effects in RF Circuits and Systems

(Georgia Institute of Technology, 2020-07-13) Ildefonso, Adrian

Space is a hostile environment for electronic systems. The levels of ionizing radiation in space can strongly limit the performance and reliability of spacecraft payloads. When energized particles pass through electronic systems, they can generate voltage and current spikes known as single-event transients (SETs). These SETs can propagate through electrical systems, disrupt their proper operation, and lead to critical issues. In practice, it is not possible to completely shield electronic systems from these particles. Thus, to ensure the proper operation of spacecraft in radiation environments, the risk of these events must be considered. There are three major phases in the risk management process: testing, assessment, and mitigation. This research presents new approaches to test, assess, and mitigate the risk of SETs in electronic systems. Novel testing techniques using ultra-fast pulsed lasers to emulate space radiation are shown. A new metric to assess the impact of SETs in communications systems is presented. Finally, several mitigation techniques for RF communications systems are shown. This work has resulted in new tools and techniques to help designers build more robust electronics for space applications. Ultimately, increasing the robustness of electronics in space systems will improve our capabilities in the areas of global communication, navigation, and space exploration.
Towards a Universal Hot Carrier Degradation Model for SiGe HBTs Subjected to Electrical Stress

(Georgia Institute of Technology, 2019-05-29) Raghunathan, Uppili Srinivasan

The objective of this work is to develop a generalizable understanding of the degradation mechanisms present in complementary Silicon-Germanium (SiGe) heterojunction bipolar transistors (HBTs) that can be used to not only predict the reliable lifetime of these devices but also overcome some of these aging limitations using clever device engineering. This broad motivation for understanding and improving SiGe HBT device reliability is explored through the following specific goals: 1) develop an understanding of the dominant hot carrier degradation sources across temperature (25 K – 573 K); 2) develop a broad understanding of all potentially vulnerable regions of damage within a SiGe HBT using electrically measured data, and how these degradations can be captured in a modeling framework; and 3) design optimized SiGe HBTs that can potentially overcome some of these device-level limitations in reliability across temperature. Being able to simulate the electrical degradation of a complex circuit with SiGe HBTs swinging dynamically on the output plane using a universal physics-based aging model is invaluable for any circuit designer optimizing for high performance and reliability.