Danielle Vanhoenacker-Janvier

Bio: Danielle Vanhoenacker-Janvier is an academic researcher from Université catholique de Louvain. The author has contributed to research in topics: MOSFET & Communication channel. The author has an hindex of 20, co-authored 154 publications receiving 1655 citations.

Accurate SOI MOSFET characterization at microwave frequencies for device performance optimization and analog modeling

Abstract: The maturation of low-cost silicon-on-insulator (SOI) MOSFET technology in the microwave domain has brought about a need to develop specific characterization techniques. An original scheme is presented, which, by combining careful design of probing and calibration structures, rigorous in situ calibration, and a new powerful direct extraction method, allows reliable identification of the parameters of the non-quasi-static (NQS) small-signal model for MOSFETs. The extracted model is shown to be valid up to 40 GHz.

Impact of Antenna Coupling on 2 $\times$ 2 MIMO Communications

Abstract: The impact of mutual coupling induced by two closely spaced minimum scattering antennas at the subscriber unit on 2 times 2 multiple-input multiple-output channels and communications is investigated. Both (de)correlation effects and variations of antenna gain resulting from coupling mechanisms are considered. Relationships between coupling and correlations/channel Frobenius norm are discussed, pointing out the role of the interelement spacing, the array orientation, and the richness of scattering. The analysis also yields useful insight into the influence of mutual coupling on capacity and system performance

Fully-Depleted SOI CMOS Technology for Low-Voltage Low-Power Mixed Digital/Analog/Microwave Circuits

Abstract: This paper demonstrates that fully-depleted (FD) silicon-on-insulator (SOI) technology offers unique opportunities in the field of low-voltage, low-power CMOS circuits. Beside the well-known reduction of parasitic capacitances due to dielectric isolation, FD SOI MOSFETs indeed exhibit near-ideal body factor, subthreshold slope and current drive. These assets are both theoretically and experimentally investigated. Original circuit studies then show how a basic FD SOI CMOS process allows for the mixed fabrication and operation under low supply voltage of analog, digital and microwave components with properties significantly superior to those obtained on bulk CMOS. Experimental circuit realizations support the analysis.

An unbiased integrated microstrip circulator based on magnetic nanowired substrate

Abstract: A very compact planar fully integrated circulator operating at millimeter wavelength has been designed using a magnetic substrate combining a polymer membrane with an array of ferromagnetic nanowires. The original feature of this substrate, called magnetic nanowired substrate (MNWS), relies on the fact that the circulation effect is obtained without requiring any biasing dc magnetic field. This leads to a significant reduction of device dimensions since no magnetic field source is needed, and a realistic ability for integration with monolithic microwave integrated circuits. The circulator design is performed by an efficient analytical model including a self design of the impedance matching network. This model also allows a physical understanding of the circulation mechanism through the access to the electromagnetic field patterns inside the circulator substrate. Based on the excellent agreement between the theoretical and experimental results, the model is used to predict the improvement of circulator performances resulting from a reduction of dielectric and conductor losses. Insertion losses lower than 2 dB with an isolation higher than 45 dB are expected for MNWS circulators with a low-loss substrate and thick metallic layers.

Mutual coupling effects on the channel capacity and the space-time processing of MIMO communication systems

Abstract: The channel capacity and the performance of MIMO systems in the presence of fading correlation and antenna coupling are investigated. Simulation results demonstrate that mutual coupling can improve the performance depending on the inter-element spacing and the richness of scattering. It is shown the bit error rate performance of spatial multiplexing is particularly influenced by the decorrelation/correlation effect caused by mutual coupling. On the other hand, the bit error rate performance of transmit diversity is mainly affected by the resulting modification of antenna gain and received power.

Review and prospects of magnonic crystals and devices with reprogrammable band structure

Abstract: Research efforts addressing spin waves (magnons) in micro- and nanostructured ferromagnetic materials have increased tremendously in recent years. Corresponding experimental and theoretical work in magnonics faces significant challenges in that spin-wave dispersion relations are highly anisotropic and different magnetic states might be realized via, for example, the magnetic field history. At the same time, these features offer novel opportunities for wave control in solids going beyond photonics and plasmonics. In this topical review we address materials with a periodic modulation of magnetic parameters that give rise to artificially tailored band structures and allow unprecedented control of spin waves. In particular, we discuss recent achievements and perspectives of reconfigurable magnonic devices for which band structures can be reprogrammed during operation. Such characteristics might be useful for multifunctional microwave and logic devices operating over a broad frequency regime on either the macro- or nanoscale.

Impact of antenna correlation on the capacity of multiantenna channels

Abstract: This paper applies random matrix theory to obtain analytical characterizations of the capacity of correlated multiantenna channels. The analysis is not restricted to the popular separable correlation model, but rather it embraces a more general representation that subsumes most of the channel models that have been treated in the literature. For arbitrary signal-to-noise ratios (SNR), the characterization is conducted in the regime of large numbers of antennas. For the low- and high-SNR regions, in turn, we uncover compact capacity expansions that are valid for arbitrary numbers of antennas and that shed insight on how antenna correlation impacts the tradeoffs among power, bandwidth, and rate.

Tunable High-Q N-Path Band-Pass Filters: Modeling and Verification

Abstract: A differential single-port switched-RC N-path filter with band-pass characteristic is proposed. The switching frequency defines the center frequency, while the RC-time and duty cycle of the clock define the bandwidth. This allows for high-Q highly tunable filters which can for instance be useful for cognitive radio. Using a linear periodically time-variant (LPTV) model, exact expressions for the filter transfer function are derived. The behavior of the circuit including non-idealities such as maximum rejection, spectral aliasing, noise and effects due to mismatch in the paths is modeled and verified via measurements. A simple RLC equivalent circuit is provided, modeling bandwidth, quality factor and insertion loss of the filter. A 4-path architecture is realized in 65 nm CMOS. An off-chip transformer acts as a balun, improves filter-Q and realizes impedance matching. The differential architecture reduces clock-leakage and suppresses selectivity around even harmonics of the clock. The filter has a constant -3 dB bandwidth of 35 MHz and can be tuned from 100 MHz up to 1 GHz. Over the whole band, IIP3 is better than 14 dBm, P1dB=2 dBm and the noise figure is 3-5 dB, while the power dissipation increases from 2 mW to 16 mW (only clocking power).

Broadband communications via high-altitude platforms: a survey

Abstract: This article is a survey on communication aspects of High Altitude Platforms (HAPs), namely airships or aircraft positioned in the stratosphere between 17 and 22 km. HAPs can be considered as a novel solution for providing telecommunications services. This survey begins with an introduction to HAPs, that is, some historical information and advantages of HAPs compared to terrestrial and satellite networks, followed by information about suitable airships and aircraft, frequency bands allocated to HAPs, possible architectures, and some points on the system structure. We continue with the studies that have been carried out on channel modeling and interference, antennas, transmission and coding techniques. We also refer to access and resource allocation techniques that have been performed so far. Finally, the survey concludes with the types of applications that HAPs are suitable for, in addition to some related projects.

Elevation Dependent Shadowing Model for Mobile Communications via High Altitude Platforms in Built-Up Areas

Abstract: An empirical propagation prediction model is described for mobile communications from high altitude platforms (HAPs) in different types of built-up areas. The model introduced here is defined as a function of the angle of elevation. The target frequencies are selected from the 2 to 6 GHz frequency band prospective for 3G and 4G mobile systems, namely at 2.0,3.5, and 5.5 GHz. This new HAP model recognizes two cases - line of sight (LOS) and non-line of sight (NLOS) between a HAP and a user at street level. The simulation of the urban environment is based on a statistical approach. Additional shadowing path loss is calculated using the uniform theory of diffraction for NLOS conditions. Normal distribution of the additional shadowing path loss was distinguishable from the simulation results. The shadowing path loss is defined as a function of the elevation angle. The results of the empirical model developed for idealized conditions are verified by measurements taken from a remote-controlled airship in different types of urban environment. Close correlation was achieved between the theoretical model and the experimental data. The HAP elevation dependent shadowing model is easy to implement and can be used for realistic planning and simulations of mobile networks provided via HAPs in built-up areas.