Kaoutar Zeljami

CHARACTERIZATION AND MODELING OF SCHOTTKY DIODES UP TO 110 GHZ FOR USE IN BOTH FLIP-CHIP AND WIRE-BONDED ASSEMBLED ENVIRONMENTS

This paper presents a wideband model, from Direct Current (DC) to W band, for a single Anode Schottky Diode based on a commercial VDI chip. Difierent measurements have been performed to obtain a complete large-signal equivalent circuit model suitable for the device under consideration up to 110GHz, and for its integration in planar circuits. The modeling has been done using a combination of DC measurements, capacitance measurements, and RF scattering measurements. The test structure for on-wafer S- parameter characterization has been developed to obtain an equivalent circuit for Coplanar to Microstrip (CPW-Microstrip) transitions, then verifled with 3D Electromagnetic (EM) tools and flnally used to de- embed device measurements from empirical data results in W band. 3D EM simulation of the diodes was used to initialize the parasitic parameters. Those signiflcant extrinsic elements were combined with the intrinsic elements. The results show that the proposed method is suitable to determine parameters of the diode model with an excellent flt with measurements. Using this model, the simulated performance for a number of diode structures has given accurate predictions up to 110GHz. Some anomalous phenomena such as parasitic resistance dependence on frequency have been found.

Contribution to the Development of Flat Fresnel Reflectors in W Band for New Imaging Applications

This work presents an experimental study in W band about the behavior of a plane Fresnel re∞ector when the feeder changes its position on the surface of a sphere whose centre is the same of the Fresnel plate zones. For this purpose, an experimental system based on seven Fresnel plate zones and two difierent levels has been developed. The center frequency of the re∞ector is 96GHz, the focal length is 100mm and height between levels is 0.78mm. Based on this Fresnel re∞ector, an experimental set up has been developed. The horn antenna feeder is flxed and situated in far fleld and the receiver is also a horn antenna located at the Fresnel focal distance. Both the re∞ector and the receiving antenna have some rotation capability to enable measurements from difierent angles. The experimental results show a good, stable behavior in gain versus the angular position of the feeder. This special property of Fresnel re∞ectors is impossible in parabolic re∞ectors and consequently, Fresnel re∞ectors could be used in new applications as radar imaging, increasing the radar fleld of view or improving the resolution by means of several squint feeders working simultaneously on the same lens or re∞ector. Therefore, the main objective of this paper is to analyze the behavior of this experimental set up for developing new Fresnel re∞ector-based applications.

Noise conversion of Schottky diodes in mm-wave detectors under different nonlinear regimes: modeling and simulation versus measurement

This paper presents and discusses several methods for predicting the low-frequency (LF) noise at the output of a mm-wave detector. These methods are based on the extraction of LF noise source parameters from the single diode under a specific set of bias conditions and the transfer or conversion of these noise sources, under different operating conditions including cyclostationary regime, to the quasi-dc output of a mm-wave detector constructed with the same model of diode. The noise analysis is based on a conversion-matrix type formulation, which relates the carrier noisy sidebands of the input signal with the detector output spectrum through a pair of transfer functions obtained in commercial software. Measurements of detectors in individual and differential setups will be presented and compared with predictions.