Andrea Bentini

GaN-Based Robust Low-Noise Amplifiers

In this paper, an overview of recently reported low-noise amplifiers (LNAs), designed, and fabricated in GaN technology is provided, highlighting their noise performance together with high-linearity and high-robustness capabilities. Several SELEX-ES GaN monolithic technologies are detailed, providing the results of the noise characterization and modeling on sample devices. An in-depth review of three LNAs based on the 0.25- μm GaN HEMT process, marginally described in previous publications, is then presented. In particular, two robust and broadband 2-18-GHz monolithic microwave integrated circuit (MMIC) LNAs are designed, fabricated, and tested, exhibiting robustness to over 40-dBm input power levels; an X-band MMIC LNA, suitable for synthetic aperture radar systems, is also designed and realized, for which measurement results show a noise figure ~ 2.2 dB with an associated gain and robustness up to 41-dBm input power level.

A novel hybrid active quasi-circulator for L-band applications

In this contribution a hybrid active quasi-circulator operating in L-Band is presented. E-pHEMT active devices mounted on ceramic substrate with copper metallization have been used. The proposed quasi-circulator is composed by active non-reciprocal phase shifters and classical passive combining structures to get the desired functionality. Insertion losses better than 2.1 dB, isolation higher than 20 dB in the 1.35 ÷ 1.65 GHz frequency band is obtained, while an isolation better than 30 dB over a 15% bandwidth. Port matching is better than 15 dB on couplers ports, while the splitter one reaches 10 dB. The overall quasi-circulator exhibits a 22 % operating bandwidth.

High-density mixed signal RF front-end electronics for T-R modules

In this contribution, several Multi-Functional Chips featuring different functionalities and integration levels are presented. A X-Band Core-Chip integrating a 6-bit attenuator, a 6-bit phase shifter, a T/R switch and a digital serial-to-parallel converter has been fabricated with 0.18 μm OMMIC ED02AH process. The MMIC exhibits 6 dB and 8 dB average insertion gain for transmit and receive mode respectively, full 360° phase coverage with 5.6° phase steps and 31.5 dB attenuation dynamic range with 0.5 dB amplitude resolution in less than 16 mm2. Two C-Band Multi-Functional Chips, one consisting of a bidirectional 6-bit phase shifter with on-board digital controls and the other integrating a 6-bit phase shifter, a buffer amplifier and a 5-bit attenuator have been fabricated with the 0.4 μm E/D GaAs process developed by SELEX Sistemi Integrati. The former exhibits full 360 degree phase coverage with 5.6° phase resolution in less than 18 mm2. The latter is an unidirectional MMIC featuring 8 dB average gain, full 360 degree phase coverage with 5.6° phase steps and 31 dB attenuation range with 1 dB amplitude resolution in less than 26 mm2.

Characterization and modeling of low-cost, high-performance GaN-Si technology

A complete characterization of HEMT devices fabricated on a GaN-on-Silicon process developed by SELEX Sistemi Integrati is presented, together with the characterization and modeling of passive elements fabricated on the same substrate. Experimental results demonstrate that the power management capability of 1-μm GaN-Si HEMTs is suitable for most high power applications; moreover, the noise performance of such devices are in line with those of 0.5-μm GaN-SiC HEMTs fabricated by the same foundry. Finally, from the passive elements characterization the suitable operating bandwidth for the MMICs based on this technology can be assessed at least up to C-band.

Design and Realization of GaAs Digital Circuit for Mixed Signal MMIC Implementation in AESA Applications

A complete design flow starting from the technological process development up to the fabrication of digital circuits is presented. The aim of this work is to demonstrate the GaAs Enhancement/Depletion (E/D) double stop-etch technology implementation feasibility for digital applications, aimed at mixed signal circuit integration. On the basis of the characterization of small E/D devices with different Gate peripheries, developed by the SELEX-SI foundry, and the analysis of several GaAs-based logical families, the most suitable logic for the available technology has been selected. Then, simple test vehicles (level shifters, NOR logic gates and D Flip-Flops) have been designed, realized, and measured to validate the design strategy applied to the GaAs E/D process. These logical circuits are preliminary to the design of a more complex serial-to-parallel converter, to be implemented onto the same chip together with RF analog blocks, such as stepped attenuators and phase shifters.

GaN-on-Silicon Evaluation for High-Power MMIC Applications

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.

An ultra-broadband 2–8 GHz GaN HEMT MMIC active combiner

In this contribution, a broadband active out-of-phase combiner designed in 0.5 μm GaN-HEMT technology developed by SELEX Sistemi Integrati is presented. The proposed MMIC is based on a distributed approach: exploiting the Drain line sharing, a dummy section and a single stage distributed amplifier, a 13.5 dB average differential gain, together with better than 10 dB input and output return losses and a CMRR better than 30 dB over the 2-8 GHz operating bandwidth are attained. The MMIC size is 2.9×3.3 mm2.

A 6–18 GHz integrated HPA-DPDT GaN MMIC

In this contribution an integrated HPA-DPDT for next generation AESA TRMs is presented. The proposed circuit relies on a concurrent design technique merging switches and HPA matching network. Realized MMIC features a 3×5mm2 outline operating in the 6-18 GHz band with a typical output power of 2W, an associated PAE of 13% and 3dB insertion loss in RX mode.