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.
DESIGN OF RF RECEIVER COMPONENTS FOR SPACE APPLICATION SUSING SIGE BICMOS

(Georgia Institute of Technology, 2021-06-25) Teng, Jeffrey Wu

The objective of the proposed research is to understand the behavior of components in SiGe BiCMOS technologies to the radiation environment present in space, and use such understanding to inform the design and testing of RF receiver components for space-flight applications. To evaluate the response of SiGe HBTs to various types of radiation, exposure to X-rays is performed to emulate operation in the space environment. Degradation in relevant device performance characteristics is considered as it changes with longer exposures. Then, implications of impaired device performance are demonstrated for circuit components commonly present in RF receivers for both radar and communications, and design considerations for operation in space are discussed.
Wideband Circuits and Antenna Designs for mm-Wave/5G Phased Arrays

(Georgia Institute of Technology, 2021-05-05) Lee, Sanghoon

The objective of this work is to present the performance and feasibility of wideband circuits and antennas for future mm-Wave phased array systems. Chapter 1 introduces the motivation of this research, first explaining the desire to operate at higher frequency regimes. Then focus is directed on the rich application spaces at mm-Wave frequencies and the corresponding need for wideband, compact, and fully integrated system-on-chip (SoC) solutions. A brief study of advanced node commercial silicon processes is also examined to demonstrate the increasing feasibility of implementing the aforementioned SoC solutions on silicon. Chapter 2 presents a design methodology of a novel ultra-compact, low-loss, and wideband mm-Wave Wilkinson Power Divider (WPD). Careful study and analysis reveal optimal and necessary design parameters and equations in terms of the coupling and mutual inductances within the structure, yielding a device that is competitive with existing literature. Chapter 3 first introduces the operation principle of spiral antennas (SA). The unique properties of SAs that make them great candidates for use in future mm-Wave phased arrays are explored. The rest of this chapter discusses the design, analysis, and results of an octagonal 4-arm Archimedean SA. Lastly, Chapter 4 provides closing remarks and discusses potential future work.
Design and Reliability of mm-Wave Circuits In Silicon-Germanium

(Georgia Institute of Technology, 2021-05-04) Moradinia, Arya

The first goal of this research is to develop a methodology for the design of RF and mm-Wave circuits in Silicon-Germanium utilizing CMOS, PIN diodes, and passive circuits. Such circuits consist of a 2-20 GHz CMOS-based TR (Transmit/Receive) SPDT switch and an 18-47 GHz Wilkinson Power Divider-Combiner (WPDC). Optimal design techniques are utilized in these circuit designs to overcome the limitations of both Front End of the Line (FEOL: active devices) and Back End of the Line (BEOL: metal stack-up) in a commercial SiGe BiCMOS processes. The resulting performances utilize novel design techniques that allow them to be competitive with existing state-of-the-art designs across multiple IC technologies. The second goal of this research is to understand the impact of DC reliability mechanisms on AC performance for analog SiGe HBT circuits and to locate an optimal DC biasing regime that balances the tradeoff between circuit reliability and performance. The circuit of interest is a DC-100 GHz wireline driver, which is widely used as a critical block in optical communications. The aim is to extend the concept of Safe Operating Area (SOA), which is the region of the DC I-V plane that does not damage a device over time, to the circuit level. This is done with the introduction of a performance-informed Circuit Safe Operating Area (C-SOA), which is defined as the region of the DC I-V plane that does not result in a degradation to AC performance over time while maintaining the best possible AC performance. The wireline driver’s highlighted AC performance is the OP1dB or output referred 1-dB compression point.
STUDY OF SINGLE-EVENT TRANSIENTS IN SILICON-GERMANIUM HETEROJUNCTION BIPOLAR TRANSISTORS

(Georgia Institute of Technology, 2021-05-04) Nergui, Delgermaa

The objective of the presented research is to investigate the effects of radiation, particularly single-event effects in silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs). First, an experimental study of single-event transients (SETs) induced by pulsed X-rays in SiGe HBTs is provided. Device-level transient data and circuit-level upset data from pulsed X-rays are analyzed and compared to those of heavy-ions. 3-D TCAD modeling is utilized to understand the source of the differences in the transients. Single-event upset (SEU) screening of shift-registers shows that X-ray can detect device sensitive nodes smaller than the beam. Second, a fully calibrated 3-D TCAD model is used to provide in-depth, time-dependent charge transport and collection mechanisms during SETs. Several hypothetical transistor designs are compared to provide insight into choosing the optimal transistor and layout design to aid in SET mitigation.