The capability to build systems entirely based on European technologies is an essential condition for all the companies working in the Defense and Space industry, in order to overcome possible problems related with the restrictions on export licenses (ITAR).For this reason from the last 40 years Selex ES Foundry has been committed to provide state-of-the-art solid state components, establishing a high level of technical capability in the design, processing and assembly of said components.In particular Selex ES Foundry is involved in a range of technological developments to consolidate and qualify half micron and quarter micron GaN technology

The benefits of using source field plate (FPS) in AlGaN/GaN HEMTs to reduce the phase distortion in efficient power amplifiers (PAs) is demonstrated in this contribution. The link between phase distortion of a PA and the drain-to-gate feedback parasitic capacitance of the transistor is shown. This link leads to critical phase nonlinearity expecially when architectures based on output load modulation, as the Doherty topology, are adopted. The FPS effect in reducing the feedback parasitic capacitance and, thus, the AM/PM distortion of the PA is verified. For experimental validation two AlGaN/GaN HEMT structures, with and without FPS, are realized and compared in order to extract the effects of FPS. Source-load pull characterizations are performed on both structures in order to verify the benefits of FPS on phase distortion, both in fixed and modulated output load conditions.

The capability to control “enabling technologies” is mandatory to overcome any restrictions on exports of critical components and therefore represents a strategic condition for the companies operating in military and aerospace market. In this scenario, Selex ES Foundry has developed and optimized GaN-HEMT process for manufacturing high power HPAs and robust LNAs as request for narrow and wide band applications up to 18GHz. The technology, based on 0.25μm gate length device, represents a high performance and reliable solution and is actually in assessment for Space Qualification.

GaN on SiC HEMTs fabricated with different gate-connected field plate structures have been tested by means of RF reliability tests. The increase in field-plate length yielded an improvement of both the dynamic and the reliability performance during RF testing. Results are thus suggesting that reliability in field-plate devices can be improved by a proper design of the field-plate geometry. (C) 2013 Elsevier Ltd. All rights reserved.

In this contribution, a high power density and efficiency C-Band hybrid power amplifier (PA), employing the GaN process developed at Selex ES, is presented. Thanks to technological improvements in the actual process, the current collapse and knee voltage shift problems are mitigated, showing 5W/mm power density at 20 V, with a linear output power increase as function of drain bias, up to 9.5W/mm at 35V. In order to assess the actual performances of the GaN HEMTs, the most representative active device has been characterized and modeled, and a PA at 5.5 GHz has been designed. The amplifier is designed utilizing second harmonic tuning strategy for high efficiency operation, thus exploiting the high-breakdown voltage peculiarity of GaN-based devices employing Field Plate technology. The PA shows an output power of 36.5 dBm with a power added efficiency (PAE) of 65 % and an associated gain of 12 dB while the preliminary evaluation estimate a MTTF of 10(7)h.

The Fluorine-based dry etching process is extensively employed in the fabrication of GaN-based High Electron Mobility Transistors. This research activity aims to the identification of the SF 6 ICP etching process effects on the performances of depletion-mode AlGaN/GaN-on-Si HEMTs. By means of reverse-bias step-stress and time-resolved constant-stress, it has been observed (i) a short-term instability under low reverse bias conditions of both threshold voltage and gate leakage current, likely related to the permanent modification of electrical configuration of the Fluorine ions implanted within the epitaxial structure during the etching process; and (ii) that the introduction of the annealing phase mitigates the described instability.

Today microwave market has identified GaN-HEMT technology as a strategic enabling technology for next generation MMICs to be implemented in high performance RF sub-assemblies such as T/R Modules, Solid State Power Transmitters, Compact Receivers, High Speed Communications. To allow commercial market entry of GaN technology, a tradeoff between high RF performance and low cost is mandatory and a possible solution is represented by GaN-on-Silicon substrate. In this scenario the evaluation of FETs RF performance and losses of passive components are demanding to understand the feasibility of GaN MMIC on Si. Following such approach, in SELEX Sistemi Integrati a 4 inches GaN-on-Si wafer containing discrete active devices and passive components has been fabricated with the 50μm Si thickness. RF FETs performance demonstrates an output power of 4W/mm @ 3GHz, while passive components characterization exhibits similar behavior of GaN SiC passive elements up to C Band.

This contribution describes the design of an ultra wide band hybrid power amplifier for applications in the frequency range from 1 GHz to 6 GHz. The amplifier is designed with a GaN-on-Si HEMT device provided by SELEX-SI, in a single ended configuration and using the source/load-pull and Scattering parameters measured data. The amplifier has been designed using a CAD oriented broad band matching approach for both input and output networks. From 1 GHz to 6 GHz, the expected output power at 3dB of gain compression is around 41 dBm.

State of the art GaN on Silicon HEMTs fabricated with and without a field-plate structure have been tested by means of DC and RF reliability tests. The introduction of the field-plate structure greatly improves device reliability both during DC as well as RF testing. Results are thus suggesting that reliability in NOFP and FP devices is mainly limited by the high electric fields within the device structure causing an increase in traps concentration.

Today, GaN-HEMT technology and Ultra Wide Band (UWB) power amplifiers are clearly identified as a strategic enabling technology for next generation MMICs to be implemented in high performance T/R Modules, Solid State Power Transmitters, Compact Receivers. To allow commercial market entry of GaN technology, a possible solution is represented by GaN-on-Silicon with a Field Plate active devices technology, in order to have a tradeoff between high RF Power performance and low cost. In this paper, a 1-7 GHz Single-Ended Power Amplifier, designed and fabricated with this technology, will be presented. The amplifier was designed by using a CAD oriented broad band matching approach for both input and output networks, and a saturated output power higher than 37 dBm is expected from measured/simulated data. The experimental load-source pull characterization in this frequency bandwidth was carried out together with a bias dependent Scattering parameters measured data.

High-resistivity Silicon substrates, thanks to their low cost and large wafer diameter, could represent a viable solution for the high power GaN-based transistors realization, even if device thermal management optimization is necessary because of thermal conductivity limitations of Silicon. In this work, a comparison between LG=0.5μm GaN on Silicon HEMT devices fabricated in Coplanar Waveguide (CPW) and Microstrip (MS) technology will be presented, showing the main differences in DC, pulsed and RF power performances related to the thermal behavior. In particular we will demonstrate that Silicon substrate thickness reduction down to 50μm results in negligible change in Power Density and PAE (>3.5 W/mm and >45% @ VDS=25 V respectively) for duty factor ranging from 1% to 50%.

In this work an experimental assessment of the electro-thermal behaviour of AlGaN/GaN HEMT on HR-Si Microstrip Technology is given. Self-heating effects and temperature rise have been evaluated on 1 mm active device periphery when HR-Si is lapped down to 50 mu m exploiting infrared thermal DC characterization method to validate thermal simulations. Maximum channel temperature and thermal resistance of the structure has been extracted at different power dissipation conditions.For the same device periphery, the Gate-to-Gate pitch influence has also been experimentally investigated and correlated to the channel temperature. Finally, relevant information about the maximum power dissipation has been pointed out, and an accurate description of the electro-thermal behaviour observed experimentally is given. (C) 2011 Elsevier Ltd. All rights reserved.

The operation at frequencies above 100GHz of electronic devices like transistors has been achieved both by using high electron mobility III-V semiconductor materials or heterostructures and by implementing fabrication techniques which strongly reduce parasitic capacitances between the device terminals, without increasing series resistances. The technology has been applied on different GaN high electron mobility transistor epiwafers, and the devices performances analyzed under their DC and RF characteristics, outlining that further semiconductor material optimization is mandatory to fully benefit the sub 1/4 micron Gate length for very high frequency operation advantage.

The design, fabrication and test of a 2-18 GHz monolithic Low Noise Amplifier utilizing 0.25 μm AlGaN/GaN HEMT technology is reported. The measured noise figure of the amplifier is less than 4.7 dB over the 2 - 18 GHz frequency range, exhibiting a minimum of 3.3 dB at 3 GHz. The LNA gain is 23 dB. Even being a low-noise amplifier, the MMIC can withstand 10W input CW RF power, demonstrating no apparent degradation: to the authors knowledge this is the best RF LNA survivability reported to date in this frequency range using GaN technology.

The development of a single bias S-band MMIC HPA designed for radar T/R module applications is reported. The chip was fabricated with a low-cost 0.5µm GaAs PHEMT process and is composed of two stages, with a final stage of 29 mm gate-width periphery. The MMIC power amplifier is designed by using a zero gate bias configuration and therefore is attractive due to the size and cost reduction. In the frequency bandwidth 2.4–3.6GHz, the HPA biased at Vd=10V delivers an output power of 20W @ 4dB of gain compression, with an associated PAE of circa 28%.

RF-MEMS represent a feasible solution to obtain very low power dissipation and insertion loss, very high isolation and linearity switch respect to "solid state" technologies. In this paper we demonstrate the possibility to fully integrate the process fabrication of RF-MEMS switches in the GaN-HEMT manufacturing steps to develop a RF-MEMS/MMIC prototype. MEMS RF performance reveals an insertion loss and an isolation respectively better than 0.6 dB and 25dB in the frequency range 5-50 GHz. Moreover the coexisting HEMT devices show a f(max)=40 GHz and 6.5 W/mm density power, demonstrating the integration achievability.

In this paper is reported the design, fabrication and test of a mixed-signal SiGe X-band multi-function control MMIC for phased array radar applications. Said MMIC, fabricated, with the ST-Microelectronics BiCMOS7RF SiGe technology, comprises a 5-bit phase shifter, 5-bit attenuator, SPDT switches, several gain amplifiers and a digital serial to parallel converter to reduce the number of MMIC I/O control lines. The gain amplifiers are implemented using SiGe HBTs, while phase shifter, attenuator and SPDT switches are based on CMOS transistors. The measurement results show a return loss better than 15 dB and a gain of 17 dB, equal in both RX and TX state. In RX mode the obtained noise figure is lower than 10 dB, while in TX mode the output P1 dB is higher than 12 dBm. The achieved RF performance, the low power consumption and associated low cost, make this SiGe control-chip an attractive solution for high performance/low cost Tx/Rx components for phased array radar applications.