MicroNimbus is a 3U CubeSat spacecraft that uses a single-chip SiGe 60 GHz radiometer to measure the temperature profile of the Earth's atmosphere. Due to the characteristics of oxygen absorption around 60 GHz, by choosing different center frequencies and bandwidths, the radiometer can measure the temperature of the atmosphere at different altitudes, giving the temperature profile. The temperature profile is of interest to weather forecasters and workers in LIDAR, and laser communications, among others. The CubeSat's low cost would allow a constellation of such spacecraft to be deployed, yielding a continuous near-real-time 3-D map of the temperature profile of the Earth's atmosphere. MicroNimbus is currently in development at the Georgia Tech Research Institute, and is expected to launch at the end of 2018.

The present work focuses on reducing dropout voltage and noise by exploiting the unique advantages of a complementary silicon-germanium (SiGe) heterojunction bipolar transistor (C-SiGe HBT) on SOI technology. We also explore the impact of utilizing different PNP device types on regulator performance. Design challenges arose from the off-chip load capacitor required to meet the specification of the instantaneous peak output voltage drop. To overcome these challenges, a right-hand plane (RHP) to left-hand plane (LHP) zero conversion technique with a nulling Miller resistor was applied. The complete solutions for the locations of the converted left-hand plane zero and the Miller pole affected by the nulling resistor were derived utilizing signal flow graphs without any assumptions commonly made in the literature. Two C-SiGe LDO regulators with two different types of PNP output devices were fabricated utilizing a commercially-available C-SiGe on SOI technology, and compared with the literature.

This paper introduces a systematic methodology for applying Mason's signal flow graph to the analysis of feedback circuits. We demonstrate that the relationships among signals of feedback circuits can be represented in a intuitive and graphical manner utilizing signal flow graphs. Once constructed, the desired solutions can be achieved by simple inspection of the signal flow graph. The Thevenin and Norton equivalent circuits are utilized to model the loading effects of the feedback network in the example circuits presented.

This paper discusses the motivation for and accomplishments to date in our ongoing effort to develop an integrated G-band SiGe radiometer for use in large-scale production of remote sensing CubeSats. The constrained nature of these platforms necessitates the use of highly integrated, low-power electronics that are well-suited for large-scale production, assembly, and testing. The high speeds of emerging 4th-generation SiGe BiCMOS technologies makes these platforms realistic targets for >100 GHz applications for the first time. The high integration level, fabrication economy-of-scale, low 1/f noise, built-in total-dose radiation tolerance, and attractive thermal properties of these technologies make them ideal for this application. Ultra-low noise SiGe LNA designs which show the potential of these technologies for use in high-quality radiometers are presented. Future designs will increase integration levels, with the ultimate goal being a full radiometer-on-a-chip containing calibration sources.

This paper demonstrates a method to achieve low input impedance and a non-constant gain-bandwidth product using SiGe NPN and PNP devices in order to attain a large bandwidth and gain in transimpedance amplifiers (TIA) for optical communication. The major obstacle to achieving wide bandwidth and high gain in a TIA design is the large parasitic capacitance associated with the input photo-diode. This challenge can be overcome by using a common-base input stage to decrease the input impedance and employing a technique to introduce a non-constant gain-bandwidth product into the system. The nonconstant gain-bandwidth product can be realized by utilizing global feedback (as opposed to local) with a common-base input stage. The circuit was designed and simulated using a complementary SiGe HBT on SOI process technology.

This paper proposes a new self-healing methodology for embedded RF amplifiers in RF sub-systems. The proposed methodology is based on oscillation principles in which the device-under-test (DUT) generates its test signature with the help of additional circuitry. In the proposed methodology, the self-generated test signature from the RF amplifier is analyzed by using on-chip resources for testing and controlling its calibration knobs to compensate for multi-parameter variations in the manufacturing process. Thus, the proposed methodology enables self-test and self-calibration/correction of RF amplifiers without the need for an external test stimulus, enabling true self-healing RF designs. The proposed methodology is demonstrated through simulations as well as measurements performed on an RF LNA, which were designed in a commercially-available SiGe BiCMOS process technology.

This paper presents an organic, lightweight X-band antenna array with integrated silicon germanium (SiGe) low noise amplifiers (LNA) and 3-bit phase shifters (PS). The SiGe LNAs and PSs were successfully integrated onto an 8×1 lightweight antenna stack-up utilizing a multilayer liquid crystal polymer (LCP) substrate. Successful comparisons of the measured and simulated results verify a working antenna array with a return loss of around 10 dB across the frequency band of 9.25 GHz - 9.75 GHz. A comparison of radiation patterns for the 8×1 antenna with integrated SiGe LNA and the 8×1 antenna with integrated SiGe LNA and PS show a 16 dB and 25 dB increase in gain, respectively. The ultimate goal is to develop an airborne X-band radar capable of a beam steering of at least ±40° through utilization of low power highly integrated SiGe electronics on a low cost multi-layer organic platform. This paper represents the first successful demonstration of a building block prototype (i.e., a fully integrated, high gain X-band antenna with SiGe LNAs and SiGe phase shifters) that can be expanded to a complete active phased array for remote sensing applications in X-band.

We present a low-voltage, low-power SiGe broadband amplifier with a bandwidth of 62 GHz, which is intended for use in 100 Gb/s Ethernet applications. The amplifier consumes only 125 mW from a 2.5 V supply. To the authors' knowledge this is the lowest reported power for a non-distributed amplifier with more than 60 GHz bandwidth in a SiGe process technology.

"Extreme environments" represents an important niche market for electronics and spans the operation of electronic components in surroundings lying outside the domain of conventional commercial, or even military, specifications. Such extreme environments would include, for instance, operation to very low temperatures (e.g., to 77 K or even 4.2 K), operation at very high temperatures (e.g., to 200/spl deg/C or even 300/spl deg/C), and operation in a radiation-rich environment (e.g., space). We argue that the unique bandgap-engineered features of silicon-germanium heterojunction bipolar transistors offer great potential to simultaneously satisfy all three extreme environment applications, potentially with little or no process modification, ultimately providing compelling cost advantages at the IC and system level.