Christopher T. Coen

On the Analysis and Design of Low-Loss Single-Pole Double-Throw W-Band Switches Utilizing Saturated SiGe HBTs

This paper describes the analysis and design of saturated silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) switches for millimeter-wave applications. A switch optimization procedure is developed based on detailed theoretical analysis and is then used to design multiple switch variants. The switches utilize IBMs 90-nm 9HP technology, which features SiGe HBTs with peak f T/ fmax of 300/350 GHz. Using a reverse-saturated configuration, a single-pole double-throw switch with a measured insertion loss of 1.05 dB and isolation of 22 dB is achieved at 94 GHz after de-embedding pad losses. The switch draws 5.2 mA from a 1.1-V supply, limiting power consumption to less than 6 mW. The switching speed is analyzed and the simulated turn-on and turn-off times are found to be less than 200 ps. A technique is also introduced to significantly increase the power-handling capabilities of saturated SiGe switches up to an input-referred 1-dB compression point of 22 dBm. Finally, the impact of RF stress on this novel configuration is investigated and initial measurements over a 48-h period show little performance degradation. These results demonstrate that SiGe-based switches may provide significant benefits to millimeter-wave systems.

Best practices to ensure the stability of sige HBT cascode low noise amplifiers

This work provides a detailed examination of the stability of SiGe cascode low noise amplifiers (LNAs). The upper base is identified as a problematic node for stability. S-probe simulations are used to extract reflection coefficients internal to the circuit and provide insight on how to improve the stability of a cascode amplifier and thereby establish “best practices” for designers. These techniques are incorporated into a cascode LNA design fabricated on a 180 nm, 150 GHz fT SiGe BiCMOS technology. The measured SiGe LNA has a gain of 16.5 dB and a noise figure of 2.1 dB at a center frequency of 9.2 GHz. A series of measurements using tuners at both the input and output confirm the LNA is stable for all impedances covered by the tuners (|Γ| <; 0.8).

An Ultra-Thin, High-Power, and Multilayer Organic Antenna Array With T/R Functionality in the

The transmit-receive (T/R) operation of an ultra-thin organic antenna array is presented at a center frequency of 9.5 GHz. High transmit power is achieved while maintaining an ultra-low profile in a novel system-on-a-package scheme whereby 32 silicon-germanium (SiGe), transmit/receive integrated-circuit (TRIC) modules have been flip-chip bonded to the array board. Each SiGe TRIC drives a pair of slot-coupled microstrip patch antennas that form an 8 × 8 rectangular array, which is all packaged in an organic substrate stack of liquid crystal polymer and RT/Duroid 5880LZ. The organic package occupies an area of 30.5 cm × 25.4 cm and has a total thickness of only 1.80 mm. The small-signal characterization of the array showed a G/T=-6.64 dB , and a measured receive gain of 20.1 dB with a variation of 0.7 dB over a 1-GHz bandwidth (BW). Finally, far-field large-signal experiments showed a measured effective isotropically radiated power of 47.1 dBm with a variation of 2.36 dB over the same BW, and without the aid of additional thermal management components.

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The single-event transient (SET) response of a SiGe-based, L-band low-noise amplifier (LNA) is investigated, with a focus on providing recommendations for radiation event simulation techniques. Pulsed-laser, two-photon absorption experiments show that the SET sensitivity of the SiGe LNA is highly dependent on operating conditions and strike location. Time and frequency-domain analyses raise potential concerns for digital data modulated on RF carrier signals. Device and circuit-level ion-strike TCAD simulations are utilized to compare alternative simulation approaches, highlight the importance of parasitics on SET simulation accuracy, and suggest best practices for modeling radiation-induced transients within RF/mm-wave circuits.

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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.

An Investigation of Single-Event Effect Modeling Techniques for a SiGe RF Low-Noise Amplifier

A 1 V supply voltage, 10-22 GHz wideband low-power low noise amplifier (LNA) is implemented in a 0.13 μm SiGe BiCMOS technology, targeting portable single-chip remote sensing radar application. This LNA exhibits a measured gain of 15.5 dB at 16 GHz and a -3 dB bandwidth of 12 GHz, while dissipating only 4 mA from a 1 V supply, with intentionally biasing the HBTs in weak saturation. The LNA has a measured noise figure (NF) of 3.4 dB at 16 GHz and less than 4.4 dB across the operating bandwidth of 10 to 22 GHz. In addition, the LNA design offers a reduced bandwidth operational mode of 10-16 GHz for interference reduction, bringing the power consumption further down to only 3 mW.

Integrated silicon-germanium electronics for CubeSat-based radiometers

This paper presents a 138-170 GHz active frequency doubler implemented in a 0.13 μm SiGe BiCMOS technology with a peak output power of 5.6 dBm and peak power-added efficiency of 7.6%. The doubler achieves a peak conversion gain of 4.9 dB and consumes only 36 mW of DC power at peak drive through the use of a push-push frequency doubling stage optimized for low drive power, along with a low-power output buffer. To the best of our knowledge, this doubler achieves the highest output power, efficiency, and fundamental frequency suppression of all D-band and G-band SiGe HBT frequency doublers to date.

A 1.0 V, 10–22 GHz, 4 mW LNA Utilizing Weakly Saturated SiGe HBTs for Single-Chip, Low-Power, Remote Sensing Applications

This paper presents a front-end switch that integrates the ability to provide both loop-back testing and transmit-receive operation. In addition, power detectors are integrated with capacitive couplers to sense the power levels at the transmitter output and the receiver input. The measured results show the power detectors have constant responsivity and can predict the power level within 0.5 dB. These capabilities are added to the front-end switch while maintaining an insertion loss of 2.3-2.5 dB and an isolation of 19.5 dB at 94 GHz.

A highly-efficient 138–170 GHz SiGe HBT frequency doubler for power-constrained applications

Small satellites are increasingly attractive platforms for performing high-quality Earth science radiometric observations. Traditional scientific satellites and instruments are extremely expensive, one-of-a-kind designs with long design cycles. In order to maintain long-term uninterrupted science data collection, re-designing new large satellites and instruments for each application every few decades may not be practical. Small satellites, however, are relatively economical and can be deployed in large constellations to collect global data with high spatial and temporal resolution. These satellites can potentially be manufactured to scale and periodically replaced, enabling practical long-term data collection. Radiometers for these platforms need to be highly integrated and suitable for scale production, assembly, and testing. This necessitates a unique instrument design.

A W-band integrated silicon-germanium loop-back and front-end transmit-receive switch for Built-in-self-test

MicroNimbus is a small satellite mission being developed by the Georgia Institute of Technology and Georgia Tech Research Institute that will utilize a frequency-agile mmwave radiometer to measure and update the temperature profile of the atmosphere from a 3U CubeSat platform. The on-board radiometer instrument will provide atmospheric temperature profile data at an altitude resolution of 10 km, a geographic resolution of 0.5°, and a temperature resolution of 2K RMS. The mission strongly aligns with the goals set forth in NASA’s Science Plan and will generate data valuable to researchers in the fields of weather forecasting, LIDAR, and laser communications. MicroNimbus has passed its Preliminary Design Review (PDR) phase and is moving towards the Critical Design Review (CDR) for the mission. If successful, MicroNimbus will serve as a first step towards the creation of a constellation of satellites designed to perform near real-time temperature profiling of the atmosphere.