A. Serino

A C-band high-efficiency second-harmonic-tuned hybrid power amplifier in GaN technology

In this contribution, a C-band 2nd harmonic tuned hybrid power amplifier utilizing a PHEMT GaN device is presented, together with technological aspects, nonlinear device model and adopted design criteria. The amplifier has been realised in hybrid form, exhibiting a bandwidth larger than 20% around 5.5GHz, with a minimum output power of 33 dBm, and a drain efficiency of 60% at the centre frequency.

GaN transistor characterization and modeling activities performed within the frame of the KorriGaN project

The present paper presents the transistor modeling work achieved in the GaN European project KorriGaN (“Key Organisation for Research in Integrated Circuits in GaN technology”). The KorriGaN project (2005–09) has released 29 GaN circuits such as high-power amplifiers (HPAs), low-noise amplifiers (LNAs), and switches. Modeling is one of the main key to reach successful designs. Therefore, nonlinear models of European GaN HEMT models have been developed. This work deals with characterization tools such as pulsed IV, pulsed [ S ] parameters, load-pull measurements, and measurement-based methods to perform GaN HEMT compact models parameters extraction. The present paper will describe the transistor modeling activities in KorriGaN for HPA designs (nonlinear models including trapping and/or self-heating effects) and LNA designs (nonlinear models and noise parameters).

A C-band high efficiency second harmonic tuned hybrid power amplifier in GaN technology

In this paper, the design, fabrication, and test of high-efficiency, high-power C-band harmonic-tuned power amplifiers in GaN technology is reported. The amplifier has been designed utilizing second-harmonic tuning for high-efficiency operation, thus exploiting the high-breakdown voltage peculiarity of GaN-based devices. Realized in a hybrid form, the amplifier has been characterized in terms of small-signal, power, and intermodulation (IMD) performance. An operating bandwidth over 20% around 5.5 GHz, with 33-dBm minimum output power, and 60% drain efficiency at center frequency is demonstrated, together with low IMD

A 20 Watt Micro-strip X-Band AlGaN/GaN HPA MMIC for Advanced Radar Applications

In this paper a first iteration design, fabrication and test of a two-stage X-Band MMIC HPA in micro-strip AlGaN/GaN technology is reported. With 20 V drain voltage operating bias point, at 3 dB compression point, the HPA delivers a pulsed output power ranging from 21 to 28.5 W, an associated gain from 12.9 to 16.5 dB and an associated PAE from circa 30% to 40%, over the 8-10.5 GHz frequency bandwidth. In the best performance frequency points (8.5 and 9 GHz) the HPA exhibits a saturated output power of 30 W with an associated PAE of 40%.

GaN Device Technology: Manufacturing, Characterization, Modelling and Verification

Gallium Nitrides superior physical properties, in comparison with other semiconductors, make GaNHEMT active devices a prime candidate in the implementation of next generation transmitters for radar systems, 3G/4G base stations and WiMAX. In this contribution, the characterization, modelling and verification of different families of high efficiency, high- power devices manufactured at SELEX Sistemi Integrati are reported. Process, characterization and modelling phases are analyzed to improve and refine the technologys fabrication techniques, thermal degradation issues and dispersion phenomena.

Novel non-linear equivalent circuit extraction scheme for microwave field-effect transistors

Non-linear equivalent circuits of microwave field-effect transistors (MESFETs, HEMTs) are now recognised to be of prime importance for the accurate design of microwave circuits, especially in monolithic technology. Many topologies have been proposed so far, together with extraction techniques [1-8]; recently, also some fundamental problems of physical consistency have been recognised and addressed [9, 10]. In the present work we propose an extended topology of the equivalent circuit that correctly represents the physical structure of the transistor and allows the fulfilment of the mentioned consistency constraints. For this circuit a practical extraction method is proposed, for the accurate and non-destructive evaluation of parasitic and intrinsic elements of the equivalent circuit. In addition, an altemative extraction method is introduced, that allows the simultaneous identification of both the bias dependent intrinsic elements and the reactive parasitic elements, at standard full-bias operating conditions.

Large-Signal modeling of power GaN HEMTs including thermal effects

In this paper a procedure to extract temperature dependent equivalent circuits for modeling the small and large signal behavior of GaN HEMTs is presented. The technique explained in this work uses pulsed I-V measurements to obtain the temperature dependence of the parameters describing the nonlinear drain current source behavior. The equivalent circuits extracted are capable of correctly modeling the DC, small signal and large signal characteristics of GaN HEMTs devices. Simulations and measurements carried out on three transistors developed by SELEX-SI are compared over a wide range of frequencies, bias and load conditions.

Evaluation of GaN HEMT Technology Development Through Nonlinear Characterization

This paper presents a comprehensive evaluation of GaN HEMT technology development on SiC substrates, relying on an electro-thermal model validated against DC, pulsed DC and S-parameter measurements. The measured devices are backside mounted, but the layout is also conceived for flip-chip mounting. Based on accurate estimation of the device thermal resistance, the model enables to explore and assess the device performances in both backside and flip-chip configurations; results are shown both for conventional ceramic AlN flip-chip mountings, and for advanced (diamond) heat sinks

Determining optimum load impedance for a noisy active 2-port network.

The role of the impedance load when dealing with noisy two port networks is investigated. Its value acts directly on input and output return losses (IRL and ORL) that can be simultaneously achieved once input load has been fixed to an arbitrary value. A novel design chart, obtained after examining constant mismatch circles, is introduced, where optimum trade-off between IRL and ORL is promptly identified. The role of degenerative source feedback is highlighted to improve IRL/ORL trade-off.

A new method for active device load equivalent circuit extraction for MMICs

Active device loads for monolithic microwave integrated circuits (MMICs) have been extensively studied and a new procedure for the extraction of their equivalent circuit has been developed. The procedure requires the availability of a coplanar three-terminal device for accurate model extraction. The new procedure is accurate, general, and easy to apply. Its validity has been demonstrated by extracting a scalable bias-dependent small-signal equivalent circuit of PHEMT-based active device loads up to 40 GHz. A good agreement between measured and modeled data has been obtained, confirming the validity and the accuracy of the proposed method.