S. Nuttinck

Bio: S. Nuttinck is an academic researcher from Philips. The author has contributed to research in topics: Noise figure & Inductor. The author has an hindex of 5, co-authored 5 publications receiving 226 citations.

Reconfigurable RFICs in Si-based technologies for a compact intelligent RF front-end

Abstract: This paper presents reconfigurable RF integrated circuits (ICs) for a compact implementation of an intelligent RF front-end for multiband and multistandard applications. Reconfigurability has been addressed at each level starting from the basic elements to the RF blocks and the overall front-end architecture. An active resistor tunable from 400 to 1600 /spl Omega/ up to 10 GHz has been designed and an equivalent model has been extracted. A fully tunable active inductor using a tunable feedback resistor has been proposed that provides inductances between 0.1-15 nH with Q>50 in the C-band. To demonstrate reconfigurability at the block level, voltage-controlled oscillators with very wide tuning ranges have been implemented in the C-band using the proposed active inductor, as well as using a switched-spiral resonator with capacitive tuning. The ICs have been implemented using 0.18-/spl mu/m Si-CMOS and 0.18-/spl mu/m SiGe-BiCMOS technologies.

Cryogenic operation of third-generation, 200-GHz peak-f/sub T/, silicon-germanium heterojunction bipolar transistors

Abstract: We present a comprehensive investigation of the cryogenic performance of third-generation silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technology. Measurements of the current-voltage (dc), small-signal ac, and broad-band noise characteristics of a 200-GHz SiGe HBT were made at 85 K, 120 K, 150 K, 200 K, and 300 K. These devices show excellent behavior down to 85 K, maintaining reasonable dc ideality, with a peak current gain of 3800, a peak cut-off frequency (f/sub T/) of 260 GHz, a peak f/sub max/ of 310 GHz, and a minimum noise figure (NF/sub min/) of approximately 0.30 dB at a frequency of 14 GHz, in all cases representing significant improvements over their corresponding values at 300 K. These results demonstrate that aggressively scaled SiGe HBTs are inherently well suited for cryogenic electronics applications requiring extreme levels of transistor performance.

Active-inductor-based low-power broadband harmonic VCO in SiGe technology for wideband and multi-standard applications

Abstract: This paper presents the first reported description, analysis, and measured performance of a wideband harmonic generation technique that utilizes the non-linearity of a tunable active inductor (TAI) in SiGe technology. The technique demonstrates the highest reported measured fundamental tuning range of 3.5 GHz, for a TAI-VCO, from 1.7-5.2 GHz (100% tuning) while consuming only 3.7 mW from a 1.8 V supply. Higher frequencies, as high as the 4th harmonics, between 3.4-8.4 GHz, are generated with output power close to or higher than that of the fundamental frequency. Detailed analysis has been performed to optimize the noise performance of the TAI, as well as to study the principle of harmonic generation.

Ultrathin-body SOI devices as a CMOS technology downscaling option: RF perspective

Abstract: Based on a careful physical description, the RF performance of ultrathin-body (down to 3 nm) silicon-on-insulator transistors is investigated. While the mobility reduction in a thin Si film slightly degrades the peak cutoff frequency and the maximum frequency of high-performance cross-coupled pair-based RF oscillators, the changes in feedback capacitance improve the low operating power and high-performance wideband and power operation of RF circuits. Also, the influence of various gate stacks on the benefits of downscaling is investigated. Fully silicided gates will enable to benefit from gate-length downscaling from an RF perspective down to 9 nm if the finger width is kept below 6 /spl mu/m, and deposited metal gates have the potential to provide advantages if the total interface resistivity is below 6-7 /spl Omega//spl middot//spl mu/m/sup 2/. Finally, the effect of series resistance at the source/drain is quantified. The device RF performance decreases by 10% per 100 /spl Omega//spl middot//spl mu/m of series resistance.

Impact of downscaling and poly-gate depletion on the RF noise parameters of advanced nMOS transistors

Abstract: For the first time, the effects of poly depletion on the RF noise performance of advanced CMOS transistors are reported and analyzed. Based on measurements and physical device simulations we quantify the increasing danger of poly gate depletion with downscaling on the RF noise parameters of CMOS devices. While poly depletion does not affect the minimum noise figure, it results in a degradation of the noise matching freedom for RFIC designers. This trend worsens with technology downscaling.

On the Potential of SiGe HBTs for Extreme Environment Electronics

Abstract: "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.

A Wide Tuning-Range CMOS VCO With a Differential Tunable Active Inductor

Abstract: By utilizing a differential tunable active inductor for the LC-tank, a wide tuning-range CMOS voltage-controlled oscillator (VCO) is presented. In the proposed circuit topology, the coarse frequency tuning is achieved by the tunable active inductor, while the fine tuning is controlled by the varactor. Using a 0.18-mum CMOS process, a prototype VCO is implemented for demonstration. The fabricated circuit provides an output frequency from 500 MHz to 3.0 GHz, resulting in a tuning range of 143% at radio frequencies. The measured phase noise is from -101 to -118 dBc/Hz at a 1-MHz offset within the entire frequency range. Due to the absence of the spiral inductors, the fully integrated VCO occupies an active area of 150times300 mum2

Cognitive Radio and Networking Research at Virginia Tech

Abstract: More than a dozen Wireless @ Virginia Tech faculty are working to address the broad research agenda of cognitive radio and cognitive networks. Our core research team spans the protocol stack from radio and reconfigurable hardware to communications theory to the networking layer. Our work includes new analysis methods and the development of new software architectures and applications, in addition to work on the core concepts and architectures underlying cognitive radios and cognitive networks. This paper describes these contributions and points towards critical future work that remains to fulfill the promise of cognitive radio. We briefly describe the history of work on cognitive radios and networks at Virginia Tech and then discuss our contributions to the core cognitive processing underlying these systems, focusing on our cognitive engine. We also describe developments that support the cognitive engine and advances in radio technology that provide the flexibility desired in a cognitive radio node. We consider securing and verifying cognitive systems and examine the challenges of expanding the cognitive paradigm up the protocol stack to optimize end-to-end network performance. Lastly, we consider the analysis of cognitive systems using game theory and the application of cognitive techniques to problems in dynamic spectrum sharing and control of multiple-input multiple-output radios.

Design of Cryogenic SiGe Low-Noise Amplifiers

Abstract: This paper describes a method for designing cryogenic silicon-germanium (SiGe) transistor low-noise amplifiers and reports record microwave noise temperature, i.e., 2 K, measured at the module connector interface with a 50-Omega generator. A theory for the relevant noise sources in the transistor is derived from first principles to give the minimum possible noise temperature and optimum generator impedance in terms of dc measured current gain and transconductance. These measured dc quantities are then reported for an IBM SiGe BiCMOS-8HP transistor at temperatures from 295 to 15 K. The measured and modeled noise and gain for both a single-and two-transistor cascode amplifier in the 0.2-3-GHz range are then presented. The noise model is then combined with the transistor equivalent-circuit elements in a circuit simulator and the noise in the frequency range up to 20 GHz is compared with that of a typical InP HEMT.

Half-terahertz operation of SiGe HBTs

Abstract: This letter presents the first demonstration of a silicon-germanium heterojunction bipolar transistor (SiGe HBT) capable of operation above the one-half terahertz (500 GHz) frequency. An extracted peak unity gain cutoff frequency (f/sub T/) of 510 GHz at 4.5 K was measured for a 0.12/spl times/1.0 /spl mu/m/sup 2/ SiGe HBT (352 GHz at 300 K) at a breakdown voltage BV/sub CEO/ of 1.36 V (1.47 V at 300 K), yielding an f/sub T//spl times/BV/sub CEO/ product of 693.6 GHz-V at 4.5 K (517.4 GHz-V at 300 K).