Aziz Ouacha

RF MEMS and GaAs Based Reconfigurable RF Front-End Components for Wide-Band Multi-Functional Phased Arrays

We study possibilities of implementing flexible and programmable components for the RF front-ends of wideband multi-functional phased arrays using GaAs MMIC and RF MEMS technologies. The use of MEMS reconfigurable matching networks in tunable bandpass LNAs is proposed to achieve wider tuning ranges (e.g. 6.5-9.9 GHz is obtained according to simulations) and adequate performance of such LNAs. We further demonstrate the potential for monolithic integration with active devices by showing how variable MEMS capacitors may be realized in a GaAs foundry process

A Wideband GAAS 6-Bit True-Time Delay MMIC Employing On-Chip Digital Drivers

This paper describes a 2-20 GHz 6-bit True-Time Delay. A total equivalent electrical length in air of 43.5 mm (145 ps) is achieved over a 2-20 GHz bandwidth. Digital drivers and a serial-to-parallel converter are integrated on the same MMIC. The ED02AH 0.2 ¿m PHEMT process from OMMIC is used. The time delay elements are realised using constant-R networks. The three smallest bits make use of a self-switched version of the constant-R networks while the 3 largest bits use a topology with single-pole double-throw (SPDT) switches and constant-R networks in the delay path. Measurement results for a typical chip are presented.

Low-noise active recursive MMIC filters

This paper presents a novel design technique that allows the noise figure of active recursive microwave filters to be reduced to a level approaching that of low-noise amplifiers (LNA). The measured noise figure of a MESFET-based 10 GHz first order MMIC filter is 4.3 dB, less than 1 dB higher than that of the LNA included in the filter. The filter is compared to a more conventional recursive filter with respect to noise and power behavior. A fifth-order filter with a simulated noise figure of 5 dB is also presented.

SE-IT joint M-AESA program: Overview and status

The Multi-function Phased Array (M-AESA) program is a joint SE-IT initiative for the development of a capability driven multifunction phased array system concept. This paper presents the progress the M-AESA research and development program has made over the last 3 years and it follows the paper “New concepts for MRFS evolutionary trends. The M-AESA program: A joint IT-SE capability driven approach” by V. Carulli et al. presented at the Radar Conference 2008 in Rome [1]. The program, based on a number of different national initiatives, benefits from different cultural approaches and perspectives, and aims to lead an initiative in Europe for such a new family of RF systems. An overview and status of this unique R&D partnership will be discussed with a mission of evaluating new technology and system architecture for developing the next generation phased array antenna system capable of exploiting the most relevant operational functions (Radar, EW and Comm) according to the operational scenarios. However, a number of technical, operational and cost issues are still remaining to be addressed before M-AESA can become a reality.

1/f noise characterization of Ir/p‐Si and Ir/p‐Si1−xGex low Schottky barrier junctions

The electrical noise properties of Ir/p‐Si and Ir/p‐Si1−xGex (x=0.14) Schottky junctions have been studied. The 1/f noise measurements were performed under forward bias over a wide temperature and frequency ranges. The effect of annealing on the noise properties of these junctions was also investigated. Annealed junction shows higher noise level. This was attributed to the defects formation at the metal/semiconductor interface. From the temperature dependence of the 1/f noise power density, an optimum operating temperature for as deposited and annealed junctions was found. The Hooge parameter, αH, is derived from the experimental data over a wide range of temperature for the deposited junctions. Values of 2.26×10−6 and 1.78×10−6 were obtained at room temperature for Ir/p‐Si and Ir/p‐Si1−xGex, respectively.

Dual Band Tunable LNA for Flexible RF Front End

This paper presents a dual band LNA that can be switched between two bands (2.4 GHz & 5.2 GHz) for IEEE 802.1 la/b/g WLAN applications. The LNA is also tunable within each band and the tuning is incorporated by on-chip varactors. The test chip consists of two fully integrated narrow-band tunable LNAs along with SPDT switch. For power saving one LNA can be switched off. The technology process is 0.2 mum GaAs offered by OMMIC. The LNA can achieve a relatively good performance over the two bands as demonstrated by simulation. With a 3V supply, the LNA has a gain of 26.2 dB at 2.4 GHz and 21.8 dB at 5.2 GHz and the corresponding NF varies between 2.07 dB and 1.84 dB, respectively. The LNA has an IIP3 of -7 dBm at 2.4 GHz and -1.6 dBm at 5.2 GHz.

Ultra wideband reconfigurable beam forming and beam shaping for radar and electronic warfare applications

Ultra wideband reconfigurable beam forming, and in particular aspects of using frequency dependent aperture area, are discussed. A schematic beam former is proposed, and two key MMIC components, a reconfigurable power splitter/combiner and a 9-bits time delay, are presented.

Wide-band circular antenna arrays consisting of bicone, semi bicone or bowtie elements

Computational results are presented for circular cylindrical antenna arrays consisting of bicone, semi bicone and bowtie elements. The presented data show that the performance of the three circular antenna arrays is very similar, and that each array covers the frequency range 6-15 GHz. For this array we can therefore use bowtie elements instead of bicone elements. This simplifies the manufacturing since bowtie elements can printed using PCB-technology.

Wideband Antenna Arrays with Reconfigurable Beamforming and Beamshaping

The paper gives an overview of research results from FOI on dual polarized phased array antennas and integrated beamforming components for wideband and wide-angle beamforming. The electromagnetic design and experimental evaluation of two antenna arrays in the 2-6 and 6-18 GHz bands, with 2 x 7 x 8 elements each, is described. The electromagnetic performance has been simulated using commercial and in-house developed codes. Experimental evaluation show that the arrays have reflection levels below -10 dB and good radiation properties in a frequency range of up to 1:3 and scan angles of up to 60deg. A concept with wideband reconfigurable beamforming with frequency tapered aperture areas is also presented. Two objectives are to enable adaptation of beamwidths to different requirements, and to enable a frequency independent beamwidth over a wide frequency range. Components for wideband beamforming with MMIC true-time delays and reconfigurable active power distribution working in the 2-18 GHz range are also presented.

Programmable microwave function array, PROMFA

This paper describes the performance of a new circuit concept, programmable microwave function array (PROMFA). The concept is based on an array of generic cells, in which a number of different functions can be realized. Each PROMFA cell is a four-port circuit, and several cells can easily be connected together in larger arrays. Simulated and measured results are presented.